Answer:
[tex]P(X>1600)=P(\frac{X-\mu}{\sigma}>\frac{1600-\mu}{\sigma})=P(Z>\frac{1600-1518}{325})=P(z>0.252)[/tex]
And we can find this probability using the z score formula and the complement rule and we got:
[tex]P(z>0.252)=1-P(z<0.252) =1-0.599= 0.401 [/tex]
[tex] z =\frac{1600-1518}{\frac{325}{\sqrt{81}}}= 2.27[/tex]
And we can find this probability using the z score formula and the complement rule and we got:
[tex]P(z>2.27)=1-P(z<2.27) =1-0.988=0.012[/tex]
Step-by-step explanation:
Let X the random variable that represent the SAT scores of a population, and for this case we know the distribution for X is given by:
[tex]X \sim N(1518,325)[/tex]
Where [tex]\mu=1518[/tex] and [tex]\sigma=325[/tex]
We want to find this probability:
[tex]P(X>1600)[/tex]
And we can use the z score formula given by:
[tex]z=\frac{x-\mu}{\sigma}[/tex]
Using this formula we got:
[tex]P(X>1600)=P(\frac{X-\mu}{\sigma}>\frac{1600-\mu}{\sigma})=P(Z>\frac{1600-1518}{325})=P(z>0.252)[/tex]
And we can find this probability using the z score formula and the complement rule and we got:
[tex]P(z>0.252)=1-P(z<0.252) =1-0.599= 0.401 [/tex]
For the other part we need to take in count that the distribution for the sampel mean if the sample size is large (n>30) is given by:
[tex]\bar X \sim N(\mu, \frac{\sigma}{\sqrt{n}})[/tex]
And we can use the z score formula given by:
[tex]z=\frac{x-\mu}{\frac{sigma}{\sqrt{n}}}[/tex]
And replacing we got:
[tex] z =\frac{1600-1518}{\frac{325}{\sqrt{81}}}= 2.27[/tex]
And we can find this probability using the z score formula and the complement rule and we got:
[tex]P(z>2.27)=1-P(z<2.27) =1-0.988=0.012[/tex]
A student used multiple regression analysis to study how family spending (y) is influenced by income
(x1), family size (x2), and additionsto savings(x3). The variables y, x1, and x3 are measured in thousands
of dollars. The following results were obtained.
ANOVA
df SS
Regression 3 45.9634
Residual 11 2.6218
Total
Coefficients Standard Error
Intercept 0.0136
x1
0.7992 0.074
x2
0.2280 0.190
x3
-0.5796 0.920
a. Write out the estimated regression equation for the relationship between the variables. (1
mark)
b. Compute coefficient of determination. What can you say about the strength of this
relationship? (3 marks)
c. Carry out a test to determine whether y is significantly related to the independent variables.
Use a 5% level of significance. (3 marks)
d. Carry out a test to see if x3 and y are significantly related. Use a 5% level of significance.
Answer:
Step-by-step explanation:
Hello!
Given the variables
Y: family spending
X₁: income of a family
X₂: family size
X₃: additions to savings of a family
And the regression output (see attachment)
The population model is Y= α + β₁X₁ + β₂X₂ + β₃X₃
a)
To write the estimated regression equation of the relationship between the variables you have to use the information given in the regression output. Under the column "coefficients", the value that corresponds to "intercept" is the estimation of the y-intercept (a), the value under X₁ corresponds to the estimation for the slop for the variable "income of the family" (b₁), under X₂ is the estimation of the slope for the variable "family size" (b₂) and under X₃ is the estimation for the slope corresponding to the variable "additions to savings" (b₃)
The estimated regression equation is:
^Y= a + b₁X₁ + b₂X₂ + b₃X₃
^Y= 0.0136 + 0.7992X₁ + 0.2280X₂ -0.5796X₃
b)
Using the SS information you can calculate the coefficient of determination as:
SStotal= SSReg+SSError= 45.9634+2.6218= 48.5852
[tex]R^2= \frac{SS_{Reg}}{SS_{Total}} = \frac{45.9634}{(48.5852)} = 0.946[/tex]
R²= 94.6%
This means that 94.6% of the variability of the average family spending is explained jointly by the family income, the family size and the addition to saving under the estimated model ^Y= 0.0136 + 0.7992X₁ + 0.2280X₂ -0.5796X₃
c)
The hypotheses are:
H₀: β₁= β₂= β₃= 0
H₁: At least one βi≠0 ∀ i=1, 2, 3
α: 0.05
The statistic for the multiple regression is
[tex]F=\frac{MS_{Reg}}{MS_{Error}} ~~F_{Df_{Reg};Df_{Error}}[/tex]
[tex]MS_{Reg}= \frac{SS_{reg}}{Df_{Reg}}= \frac{45.9634}{3} = 15.32[/tex]
[tex]MS_{Error}= \frac{SS_{Error}}{Df_{Error}} = \frac{2.6218}{11} = 0.238[/tex]
[tex]F_{H_0}= \frac{MS_{Reg}}{MS_{Error}}= \frac{15.32}{0.238}= 64.37[/tex]
p-value < .00001
At a 5% significance level, there is enough evidence to reject the null hypothesis. This means that the family income, family size and the addition to savings modify jointly the average spending of families.
d.
Individual tests:
There are two possible statistics to test the significance of each independent variable: [tex]t= \frac{b_i-\beta_i }{S_{b_i}} ~~t_{n-3}[/tex] ∀ i= 1, 2, 3, or [tex]F=\frac{MS_{X_i}}{MS_{Error}} ~F_{Df_{X_i}; Df_{Error\\}}[/tex]
Since the output doesn't give us the information of the individual ANOVA, you have to use the t-test (Df: n-3= 12-3= 9) for these hypotheses. Using the p-value approach. the decision rule for the three hypothesis will be:
If p-value ≤ α ⇒ Reject null hypothesis.
If p-value > α ⇒ Do not reject the null hypothesis.
1)
H₀: β₁ = 0
H₁: β₁ ≠ 0
α: 0.05
[tex]t_{H_0}= \frac{b_1-\beta_1 }{Sb_1}= \frac{0.7992-0}{0.074}= 10.8[/tex]
p-value < .00001 ⇒ Decision is to reject the null hypothesis.
2)
H₀: β₂ = 0
H₁: β₂ ≠ 0
α: 0.05
[tex]t_{H_0}= \frac{b_2-\beta_2 }{Sb_2}= \frac{0.2280-0}{0.190}= 1.2[/tex]
p-value: 0.260773 ⇒ The decision is to not reject the null hypothesis.
3)
H₀: β₃ = 0
H₁: β₃ ≠ 0
α: 0.05
[tex]t_{H_0}= \frac{b_3-\beta_3 }{Sb_3}= \frac{-0.5796-0}{0.920}= -0.63[/tex]
p-value: 0.544355 ⇒ The decision is to not reject the null hypothesis.
So, at a 5% significance level, it seems that the three independent variables influence jointly the variation on the average spending of the families, but looking at them separately, only the income of the families seems to affect their spending habits significantly while the family size or their addition to savings don't seem to have major effect over their spending habits.
I hope this helps!
tan 12 = 22/x
Please help !!! Last answer says 4.7
Answer:
103.5
Step-by-step explanation:
Multiply x on both sides
xtan12 = 22
Now divide tan12 to isolate x
x = (22) / (tan(12))
Now we know that calculator should be in degree mode because the answer choices do not have the radian mode answer. When your calculator is in Degree mode and you calculate this value you get approximately 103.5
The value of x if tan 12 = 22/x is 103.5
Given the trigonometric expression:
tan 12 = 22/x
We need to get the value of "x"
Cross multiply
x tan12 = 22
x = 22/tan12
x = 22/0.2126
x = 103.529
Hence the value of x if tan 12 = 22/x is 103.5
Learn more here: https://brainly.com/question/25618616
If the ratio of the ages of Kissi and Esinam is 3:5 and that of Esinam and Lariba is 3:5 and the sum of the ages of all 3 is 147 years, what is the age difference between oldest the youngest?
Answer:
48
Step-by-step explanation:
Esinam shere a common ratio hence,
the lcm of 3 and 5 is 15
Kissi:Esinam= 9:15 and Esinam:Lariba=15:25
Combining; 9:15:25
Let x be the ages such that,
Kissi=9x and Esinam=15x and Lariba=25x
9x+15x+25x=147
49x=147
x=3
Youngest; Kissi=9x=9(3)=27
Oldest; Lariba=25x=25(3)=75
Difference 75-27=48
What is the result of converting 81 inches to feet ? Remember, there are 12 inches in a foot.
A) 69 feet
B) 8.1 feet
C) 7.25 feet
D) 6.75 feet
Answer:
6.75 ft
Step-by-step explanation:
81 inches
We know there are 12 inches in 1 ft
81 inches * 1 ft/ 12 inches = 81/12 ft =6.75 ft
Fernando bought 8 pints of milk. How many fluid ounces of milk did Fernando buy? A. 16 fluid ounces B. 64 fluid ounces C. 128 fluid ounces D. 256 fluid ounces
Answer:
C.
Step-by-step explanation:
There are 16 ounces in a pint. 8 * 16 = 128
what is the last three
Answer:
20:30 goes to 8:12
the rest goes to 6:18
Step-by-step explanation:
i may be wrong
Answer:
7:12 is equivalent to 6:18
20:30 is equivalent to 8:12
5:15 is equivalent to 6:18
Step-by-step explanation:
plz mark brainliest
1. If the ratio of the ages of Kissi and Esinam is 3:5 and that of Esinam and Lariba is 3:5 and
the sum of the ages of all 3 is 147 years, what is the age difference between oldest the
youngest?
Ans: years
2. The HCF of two numbers is 11, and their L.C.M is 368. If one number is 64, then the other
number is ….
Answer:
1) 48 years.
2) Question incorrect.
11 isn't a factor of 64, and 368 isn't a multiple of 64. 11 also isn't a factor of 368, hence, it would be impossible to find the unknown second number with all of these false information in the question.
Step-by-step explanation:
Let the ages of Kissi, Esinam and Lariba be x, y and z respectively.
Ratio of the ages of Kissi and Esinam is 3:5
x:y = 3:5
(x/y) = (3/5)
5x = 3y
x = (3y/5) (eqn 1)
Ratio of the ages of Esinam and Lariba is 3:5
y:z = 3:5
(y/z) = (3/5)
5y = 3z
z = (5y/3) (eqn 2)
The sum of their 3 ages is 147
x + y + z = 147 (eqn 3)
Substituting the values of x and z from eqn 1 and 2 into eqn 3, we have
(3y/5) + y + (5y/3) = 147
(49y/15) = 147
y = (147×15/49) = 45.
x = (3y/5) = (3×45/5) = 27
z = (5y/3) = (5×45/3) = 75
The ages of Kissi, Esinam and Lariba are then 27, 45 and 75 respectively.
The difference in the ages of the oldest amf the youngest is thus, 75 - 27 = 48 years.
2) This question seems to be faulty and incorrect as 11 isn't a factor of 64, and 368 isn't a multiple of 64. 11 also isn't a factor of 368, hence, it would be impossible to find the unknown second number with all of these false information in the question.
Hope this Helps!!!
How would you use a completely randomized experiment in each of the following settings?
Is a placebo being used or not? Be specific and give details.
a. A charitable nonprofit organization wants to test two methods of fund-raising. From a list of 1000 past donors, half will be sent literature about the successful activities of the charity and asked to make another donation. The other 500 donors will be contacted by phone and asked to make another donation. The percentage of people from each group who make a new donation will be compared.
b. A tooth-whitening gel is to be tested for effectiveness. A group of 85 adults have volunteered to participate in the study. Of these. 43 are to be given a gel that contains the tooth-whitening chemicals. The remaining 42 are to be given a similar-looking package of gel that does not contain the tooth-whitening chemicals. A standard method will be used to evaluate the whiteness of teeth for all participants. Then the results for the two groups will be compared. How could this experiment he designed to be double-blind?
c. Consider the experiment described in part (a). Describe how you would use a randomized block experiment with blocks based on age. Use three blocks: donors younger than 30 years old. donors 30 to 59 years old. donors 60 and older.
Answer:
Step-by-step explanation:
a. Two methods of fund raising is being tested here in the first case study. To make a completely randomized experiment. I would use and randomly assign half the population of the 1000 donor sample that will be sent literature about the successful activities of the charity and asked to make another donation to one of the two treatment conditions: which is a sent literature about the successful activities of the charity. While the placebo group would be the other 500 donors contacted by phone and asked to make another donation with no influence whatever from the charity.
b. For the second case study, To make a completely randomized experiment. I would use and randomly assign 43 particupants which are to be given a gel that contains the tooth-whitening chemicals to the treatment condition containing the tooth-whitening chemicals while the placebo group would be the remaining 42 which are to be given a similar-looking package of gel that does not contain the tooth-whitening chemicals.
c. Using three blocks: the completely randomized design experiment would be:
Donors younger than 30 years old:
Sent literature: Yes No
Contact by phone: Yes No
Donors 30 to 59 years old:
Sent literature: Yes No
Contact by phone: Yes No
Donors 60 and older:
Sent literature: Yes No
Contact by phone: Yes No
(Yes means yes to another donation and No means no to another donation)
Answer:
Step-by-step explanation:
a. Two methods of fund raising is being tested here in the first case study. To make a completely randomized experiment. I would use and randomly assign half the population of the 1000 donor sample that will be sent literature about the successful activities of the charity and asked to make another donation to one of the two treatment conditions: which is a sent literature about the successful activities of the charity. While the placebo group would be the other 500 donors contacted by phone and asked to make another donation with no influence whatever from the charity.
b. For the second case study, To make a completely randomized experiment. I would use and randomly assign 43 particupants which are to be given a gel that contains the tooth-whitening chemicals to the treatment condition containing the tooth-whitening chemicals while the placebo group would be the remaining 42 which are to be given a similar-looking package of gel that does not contain the tooth-whitening chemicals.
c. Using three blocks: the completely randomized design experiment would be:
Donors younger than 30 years old:
Sent literature: Yes No
Contact by phone: Yes No
Donors 30 to 59 years old:
Sent literature: Yes No
Contact by phone: Yes No
Donors 60 and older:
Sent literature: Yes No
Contact by phone: Yes No
(Yes means yes to another donation and No means no to another donation)
An item is regularly priced at 40$. It is. On sale for 30% off the regular price. How much (in dollars) is discounted from the regular price?
Answer:
Step-by-step explanation:
12$
20000 rupees to US dollars
Answer: $264.54
Hope this helped! God bless!
round 0.004198223 to 3 significant figures
I will give brainliest
Answer:
0.00420 is the answer
Step-by-step explanation:
The definition of sig figs is each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first nonzero digit.
The rounding number of 0.004198223 to 3 significant figures is 0.0042
Here,
The number is 0.004198223.
We have to find, 0.004198223 to 3 significant figures.
What is Rounding number?
Rounding means making a number simpler but keeping its value close to what it was.
Here,
The number is 0.004198223.
To find 3 significant figures,
We round a number to three significant figures in the same way that we would round to three decimal places.
Then, We count from the first non-zero digit for three digits. We then round the last digit.
Here, the digit is 9 then it will be round.
We get, the number is;
0.0042
We fill in any remaining places to the right of the decimal point with zeros.
So, The rounding number of 0.004198223 to 3 significant figures is 0.00420
Learn more about the rounding number visit:
https://brainly.com/question/4896544
#SPJ2
Marcus is trying to find 4 5/6-1 3/6. His work shown. What is Marcus's mistake?
Step 1: Subtract the wholes. 4-1=3
Step 2: Subtract the fractions. 5/6-3/6=2/6
Step 3: Subtract the differences. 3-2/6=2 4/6
Answer:
Step 3
Step-by-step explanation:
The mistake was made in Step 3.
Step 1: Subtract the wholes. 4 - 1 = 3
Step 2: Subtract the fractions. 5/6 - 3/6 = 2/6
After Step 2, He should have added them instead of subtracting them:
3 + 2/6 = 3 2/6
So, step 3 was his mistake.
Answer:step 3
Step-by-step explanation: he should have added
how do you add 9 1/6 + 2 1/12
Answer:
11 1/4
Step-by-step explanation:
first make the fractions equal. So 9 1/6 would be 9 2/12 so that we canadd them together.
9 2/12 + 2 1/12 = 11 3/12
but u can simplify the answer so itll be 11 1/4
[tex]answer = 11 \ \frac{3}{12} \\ solution \\ 9 \ \frac{1}{6} + 2 \ \frac{1}{12} \\ = \frac{55}{6} + \frac{25}{12} \\ = \frac{55 \times 2 + 25}{12} \\ = \frac{110 + 25}{12} \\ = \frac{135}{12} \\ = 11 \ \ \frac{3}{12} \\ hope \: it \: helps[/tex]
Use the distributive property to remove the parentheses .
-8(y-v-3)
Answer:
-8y +8v +24
Step-by-step explanation:
-8(y-v-3)
Multiply each term inside the parentheses by -8
-8y -v*-8 -3*-8
-8y +8v +24
___________________________________
Hey!!!
solution,
-8(y-v-3)
= -8y+8v+24
_________________________________
Here,
You have to remember these things:
(+)*(+)=(+)(+)*(-)=(-)(-)*(-)=(+)(-)*(+)=(-)Hope it helps.
Good luck on your assignment
a courtroom spectator merely looks at the defendant and says, “He’s guilty, i tell you.”
Answer:
hes lyin prolly
Step-by-step explanation:
The lengths of pregnancies in a small rural village are normally distributed with a mean of 267 days and a standard deviation of 15 days. A distribution of values is normal with a mean of 267 and a standard deviation of 15. What percentage of pregnancies last beyond 246 days? P(X > 246 days) =
Answer:
91.92% of pregnancies last beyond 246 days
Step-by-step explanation:
When the distribution is normal, we use the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this question, we have that:
[tex]\mu = 267, \sigma = 15[/tex]
What percentage of pregnancies last beyond 246 days?
We have to find 1 subtracted by the pvalue of Z when X = 246. So
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{246 - 267}{15}[/tex]
[tex]Z = -1.4[/tex]
[tex]Z = -1.4[/tex] has a pvalue of 0.0808
1 - 0.0808 = 0.9192
91.92% of pregnancies last beyond 246 days
New York State's "Quick Draw" lottery moves right along. Players choose between one and 10 numbers from the range one to 80; 20 winning numbers are displayed on a screen every four minutes. If you choose just one number, your probability of winning is 20/80, or 0.25. Lester plays one number fourteen times as he sits in a bar. What is the probability that all fourteen bets lose
Answer:
0.0178
Step-by-step explanation:
For computation of probability that all fourteen bets lose first we need to find out the Probability of losing in 1 bet is shown below:-
Probability of losing in 1 bet = 1 - P(winning)
= 1 - 0.25
= 0.75
With the help of probability of losing in 1 bet we can find out the Probability of losing in 8 bets which is here below:-
= Probability of losing in 1 bet ^ Number of loosing bets
= 0.75 ^ 14
= 0.017817948
or
= 0.0178
Therefore for computing the probability that all fourteen bets lose we simply applied the above formula.
Solve Ixl >-9
No solution
All reals
(X|X<-9 or X>9)
Answer:
all reals
Step-by-step explanation:
all reals as |x| >= 0 for every x real
so |x| > -9 is always true
In △ ABC, ∠C = 57° and ∠A = 103°. Side CB= 6.5 cm. Draw △ A′B′C′ under the same condition as △ ABC. Leave all construction marks as evidence of your work, and label all side and angle measurements(use text box). What can you conclude about △ ABC and △ A′B′C′? Justify your response.
Answer:
ΔA'B'C' is congruent to ΔABC
Step-by-step explanation:
See attached for the construction of ΔA'B'C'. (The vertices are labeled ABC.)
We computed angle B to be ...
∠B = 180° -∠A -∠C
∠B = 180° -103° -57° = 20°
We constructed segment BC of length 6.5. Then we constructed angles of 20° and 57° from B and C, respectively. The location where the rays from those angles cross is point A', and the angle there is 103°, as required.
__
ΔA'B'C' is congruent to ΔABC by the ASA congruence postulate.
2 Points
Which is a kingdom?
O A. Prokarya
B. Protista
C. Mammalia
O D. Chordata
Answer:
Protista
Step-by-step explanation:
Archaebacteria.
Eubacteria.
Protista.
Fungi.
Plantae.
Animalia.
These are the 6 kingdoms
The radius of the large sphere is double the radius of the
small sphere.
How many times is the volume of the large sphere than the
small sphere?
02
O4
6
O 6
O 8
Answer:
8
Step-by-step explanation:
just do the comparation
Vb : Vs
b for big and s for small
4/3 π rb³ : 4/3 π rs³ (since there are 4/3 and π on both side, we can eliminate them so)
Vb : Vs = rb³ : rs³
Vb : Vs = (2rs)³ : rs³
Vb : Vs = 8rs³ : rs³ (delete the r³ on both side)
Vb : Vs = 8 : 1
so Vb is 8 times larger in volume than the small one
Help, please. I dont really understand
Answer:
We can eliminate the second and third options because marking something up doesn't result in a number less than the original. Since we are told to select 3 options and there are 3 answer choices left we select the first, fourth, and fifth statements.
A fair spinner has 11 equal sections: 3 red, 4 blue and 4 green. It is spun twice. What is the probability of getting the same colour twice?
Answer:
The probability of getting the same colour twice is approximately 34%.
Step-by-step explanation:
The probability of getting each color is:
P(x=red) = 3/11 P(x=blue) = 4/11P(x=green) = 4/11Then, we can calculate the probability of getting the color red twice as:
[tex]P(x_1=R;x_2=R)=P(x=R)^2=(3/11)^2=9/121[/tex]
We have to repeat this for the color blue and green:
[tex]P(x_1=B;x_2=B)=P(x=B)^2=(4/11)^2=16/121\\\\P(x_1=G;x_2=G)=P(x=G)^2=(4/11)^2=16/121[/tex]
Then, the probability of getting the same color twice in two spins can be calculated as:
[tex]P=P(x_1=R;x_2=R)+P(x_1=B;x_2=B)+P(x_1=G;x_2=G)=\\\\P=9/121+16/121+16/121\\\\P=41/121\approx0.34[/tex]
solve for x
x/9=3
whats x
Answer:
x = 27
Step-by-step explanation:
x/9 = 3
Multiply each side by 9
x/9 * 9 = 3*9
x = 27
Answer:
27
Step-by-step explanation:
x/9= 3
Carry over the 9 and make x the subject.
x= 3*9
x= 27
Therefore x is 27.
To check if the answer is correct, replace the x with the value of what it is in brackets. The value of x is 27.
(27)/9= 3
= 27/9
= 3
We got back the 3 so that means the answer is correct
How many seconds in oneday
Answer:
there are 86,400 seconds in one day
2x2 + 3x ANSWER TO THIS
Answer:
x(2x+3)
Step-by-step explanation:
Im guessing 2x2 is 2x^2
2x^2 + 3x = 0
x(2x+3)
A circular plate has circumference of 37.7cm. Calculate the diameter of the plate
Anyone that answers I will mark as brilliant
Answer:
12.0
Step-by-step explanation:
d(pi)=37.7
d=12.0
Round the following number to the nearest thousand 2385
By rounding of the following number to the nearest thousand is 2000.
What is rounding a number to some specific place?Rounding some number to a specific value is making its value simpler (therefore losing accuracy), mostly done for better readability or accessibility.
'
Rounding to some place keeps it accurate on the left side of that place but rounded or sort of like trimmed from the right in terms of exact digits.
Round the following number to the nearest thousand
2385
= 2000
Thus, by rounding of the following number to the nearest thousand is 2000.
Learn more about rounding numbers here:
https://brainly.com/question/1285054
#SPJ2
the graph of f (x) shown below has the same shape as the graph of G (x) equals x ^ 4 but it is shifted 4 units to the right what is the equation
Answer:
D
Step-by-step explanation:
shifting 4 units to the right means that the new root = old root + 4
what that means is that the equation must have a transformation such that it equates to 0 with the root being 4 larger.
the root/vertex for x^4 is at x=0
we want the root to be at x=4
so that means we can subtract 4 from x
and get (x-4)^4
The first digit in any number must be 1, 2, 3, 4, 5, 6, 7, 8, or 9 because we do not write numbers such as 15 as 015. While it is reasonable to think that for most real-life data each digit occurs with equal frequency so that each digit 1, 2, ..., 9 has probability 1/9 of being the first digit, this is not true. It is a surprising phenomenon that in many naturally occurring numbers and web-based data the first digit has a probability distribution known as Benford's law.
Benford's law, also called the first-digit law, states that in lists of numbers from many (but not all) real-life sources of data, the leading digit is distributed in a specific, non-uniform way.
Specifically, for d = 1, 2, 3, 4, 5, 6, 7, 8, 9, Benford's law states P(first digit is d) = log_10(1+(1/d)) . The distribution of the first digit according to Benford's law, calculated to 3 decimal places, is shown in the table below.
Benford's law
First Digit X 1 2 3 4 5 6 7 8 9
Probability .301 .176 .125 .097 .079 .067 .058 .051 .046
Benford's Law and the Equally Likely Model benford equally likely
The law is named after physicist Frank Benford, who stated it in 1938, although it had been previously stated by Simon Newcomb in 1881. A surprising variety of data from the natural sciences, social affairs, and business obeys Benford's law.
This result has been found to apply to a wide variety of data sets, including electricity bills, street addresses, stock prices, population numbers, death rates, lengths of rivers, physical and mathematical constants, and processes described by power laws (which are very common in nature).
Numbers that are assigned, such as social security numbers and zip codes, or data with a fixed maximum, such as deductible contributions to individual retirement accounts, or randomly generated numbers, do not follow Benford's law.
The figure below shows how the distribution of the first digit of various naturally occurring and web-based data compares with Benford's law.
benford natural data web data
Figure information. Earthquakes: depth in km of 248,915 quakes, 1989-2009; source National Earthquake Information Center, United States Geological Survey. Minnesota lakes: size in acres of approx. 1100 lakes; source Wikipedia. Births: number of births in each county of the United States (approximately 3200), 2010; source: US Census Bureau. Diggs: total number of diggs for each of the top 1000 diggers at digg.com; source: socialblade.com.
Question 1:
(1a). What is the expected value of the first digit when the first digit follows Benford's law?
expected value (Use 3 decimal places).
(1b). What is the expected value of the first digit when the possible first digits are equally likely?
expected value (Use 3 decimal places).
(1c). What is the standard deviation of the first digit when the first digit follows Benford's Law?
Answer:
0.699
Step-by-step explanation:
got it on khan academy, should get brainliest thanks
