Answer:
(A)[tex]2^n[/tex]
Step-by-step explanation:
Given a set with "n" number of elements, the collection of all subsets of the set is referred to as the Power set of the given set.
To find the number of possible subsets of any set, we use the formula: [tex]2^n[/tex]
Take for example the set: A={2,3,4)
A has 3 elements, therefore n=3
The number of possible subsets of A is: [tex]2^3=8$ subsets[/tex]
Steve wants to use his 18% employee discount to buy a video game that has a regular price of $69.99. A 6.5% sales tax is applied to the discounted price. How much will he pay for the game, including sales tax?
Answer:
$61.12
Step-by-step explanation:
Price of the Video game = $69.99
Discount = 18%
Discount price = 18% of $69.99
= $69.99*18/100
= $12.6
Price after Discount = Price - Discount price
= $69.99 - $12.6
= $57.39
Sales tax = 6.5% applied to the discounted price
= 6.5% of $57.39
sales tax in dollars = $57.39 * 6.5/100
= $3.73
The amount he pays for the game = $57.39 + $3.73
= $61.12
Solve the equation and state a reason for each step.
23+11a-2c=12-2c
Simplifying
23 + 11a + -2c = 12 + -2c
Add '2c' to each side of the equation.
23 + 11a + -2c + 2c = 12 + -2c + 2c
Combine like terms: -2c + 2c = 0
23 + 11a + 0 = 12 + -2c + 2c
23 + 11a = 12 + -2c + 2c
Combine like terms: -2c + 2c = 0
23 + 11a = 12 + 0
23 + 11a = 12
Solving
23 + 11a = 12
Solving for variable 'a'.
Move all terms containing a to the left, all other terms to the right.
Add '-23' to each side of the equation.
23 + -23 + 11a = 12 + -23
Combine like terms: 23 + -23 = 0
0 + 11a = 12 + -23
11a = 12 + -23
Combine like terms: 12 + -23 = -11
11a = -11
Divide each side by '11'.
a = -1
Simplifying
a = -1
A hose fills a hot tub at a rate of 3.84 gallons per minute. How many hours will it take to fill a 305-gallon hot tub?
Answer:
1.56 hours
Step-by-step explanation:
300 gal × 1 min 3.2 gal × 1 hr 60 min = 1.56 hr.
Answer:
i thought the question said a 'HORSE' fills a hot tub...
Step-by-step explanation:
lol dont mind me i just want points :D
Mario’s Restaurant is planning to tile the floor of their outdoor dining area, represented by the composite figure below. The tile costs $1.50 per square foot. How much should the restaurant plan to spend on tile to complete the job?
Answer:
Cost of tiling the floor of the restaurant = $346.5
Step-by-step explanation:
Since Mario's restaurant is in the shape of a composite figure.
Area of the composite figure = Area of the rectangle + Area of trapezoid
Area of the rectangle = 3 × 9
= 27 square feet
Area of the trapezoid = [tex]\frac{1}{2}(b_{1}+b_{2}).h[/tex]
Here [tex]b_{1}[/tex] and [tex]b_{2}[/tex] are the parallel sides of the trapezoid and 'h' is the distance between these sides.
Area of the trapezoid = [tex]\frac{1}{2}[12+(31-9)]\times 12[/tex]
= 17 × 12
= 204 square feet
Total area of the floor = 27 + 204
= 231 square feet
Cost of the tiles = $1.5 per square feet
Total Cost of tiling the floor of Mario's restaurant will be,
= per square feet cost × Area of the floor
= 1.50 × 231
= $346.5
Answer:
THE ANSWER IS .B 346.50
Step-by-step explanation:
g Gravel is being dumped from a conveyor belt at a rate of 10 ft3/min, and its coarseness is such that it forms a pile in the shape of a cone whose base diameter and height are always equal. How fast is the height of the pile increasing when the pile is 6 ft high
Answer:
0.3537 feet per minute.
Step-by-step explanation:
Gravel is being dumped from a conveyor belt at a rate of 10 ft3/min. Since we are told that the shape formed is a cone, the rate of change of the volume of the cone.
[tex]\dfrac{dV}{dt}=10$ ft^3/min[/tex]
[tex]\text{Volume of a cone}=\dfrac{1}{3}\pi r^2 h[/tex]
If the Base Diameter = Height of the Cone
The radius of the Cone = h/2
Therefore,
[tex]\text{Volume of the cone}=\dfrac{\pi h}{3} (\dfrac{h}{2}) ^2 \\V=\dfrac{\pi h^3}{12}[/tex]
[tex]\text{Rate of Change of the Volume}, \dfrac{dV}{dt}=\dfrac{3\pi h^2}{12}\dfrac{dh}{dt}[/tex]
Therefore: [tex]\dfrac{3\pi h^2}{12}\dfrac{dh}{dt}=10[/tex]
We want to determine how fast is the height of the pile is increasing when the pile is 6 feet high.
[tex]When h=6$ feet$\\\dfrac{3\pi *6^2}{12}\dfrac{dh}{dt}=10\\9\pi \dfrac{dh}{dt}=10\\ \dfrac{dh}{dt}= \dfrac{10}{9\pi}\\ \dfrac{dh}{dt}=0.3537$ feet per minute[/tex]
When the pile is 6 feet high, the height of the pile is increasing at a rate of 0.3537 feet per minute.
Angle 6= (11x+8) and angle 7=(12x-4) what is the measure of angle 4
Answer:
Answer is m∠4=40
Step-by-step explanation:
take note that m∠6 & m∠7 are vertical angles. Vertical angles are equal to each other, therefore m∠6 is equal to m∠7.
m∠6 = m∠7 (vertical angles)
11x + 8 = 12x – 4
12x - 11x = 8 + 4
x = 12
so
m∠6 = 11x + 8
m∠6 = 11(12) + 8
m∠6 = 132 + 8
m∠6 = 140
m∠4 = 180 - m<6
m∠4 = 180 - 140
m∠4 = 40
Answer:
A
Step-by-step explanation: Took test
If theta=3pi/4
Sin theta=?
Cos theta=?
Answer:
For ease of writing, θ [tex]=x[/tex]
[tex]sin(x)=\frac{1}{\sqrt{2} }[/tex]
[tex]cos(x)=-\frac{1}{\sqrt{2} }[/tex]
Step-by-step explanation:
Our angle is [tex]x=\frac{3\pi }{4}[/tex]
To find our answers for [tex]sin(\frac{3\pi}{4} )[/tex] and [tex]cos(\frac{3\pi}{4} )[/tex], we will need to use a unit circle. (I have attached the image of one).
Recall that the [tex]sin[/tex] of an angle is equal to the y-value of the corresponding ordered pair.
And the [tex]cos[/tex] of an angle is equal to the x-value of the corresponding ordered pair.
For the angle [tex]x=\frac{3\pi }{4}[/tex], the ordered pair is [tex](-\frac{1}{\sqrt{2}} }, \frac{1}{\sqrt{2} } )[/tex]
This means that
[tex]sin(x)=\frac{1}{\sqrt{2} }[/tex]
[tex]cos(x)=-\frac{1}{\sqrt{2} }[/tex]
Describe the rate of change of f(x)=lnx. Your answer should explain how the slope changes when x is small and when x is large.
Answer:
By plotting the graph of f(x)=lnx, you can conclude that when x is small, dy/dx has a larger value. For instance, the gradient of the curve when x=0.5 is 2. However, as you move along the x axis, you will see that the graph levels off, indicating a decrease in the slope, or dy/dx. For example, if x=10, dy/dx = 0.1 and when x=20, dy/dx= 0.05 and so on. Eventually, when x is large enough the value of dy/dx will be negligible.
Thus, as x increases, the slope decreases.
Answer:
Explanation shown below
Step-by-step explanation:
f(x)=lnx;
The rate of change is defined as dy/dx;
dy/dx[Inx] = 1/x
and dy/dx is defined as the slope
The nature of the slope is as x increases ; the slope decreases and conversely meaning as x decreases, the slope increases.
A construction company has to complete a project no later than 4 months from now or there will be significant cost overruns. The manager of the construction company believes that there are four possible values for the random variable X, the number of months from now it will take to complete this project: 2, 2.5, 3, and 3.5. It is currently believed that the probabilities of these four possibilities are .4, .3, .2, and .1, respectively. What is the expected completion time (in months) of this project from now?
Answer:
The expected completion time of this project from now is 2.5 months.
Step-by-step explanation:
To find the expected completion time for the project, we multiply each projection by it's probability.
We have that:
0.4 = 40% probability it takes 2 months to complete the project.
0.3 = 30% probability that it takes 2.5 months to complete the project.
0.2 = 20% probability it takes 3 months to complete the project.
0.1 = 10% probability it takes 3.5 months to complete the project.
What is the expected completion time (in months) of this project from now?
E = 0.4*2 + 0.3*2.5 + 0.2*3 + 0.1*3.5 = 2.5
The expected completion time of this project from now is 2.5 months.
1. What is the approximate area of a circle with a diameter of 20 inches?
2. What is the volume of a cube with a side length of 3 cm?
3. What is the median of the data set { 35,20, 30,25,20 }?
Answer:
1. 100[tex]\pi[/tex]
2. 27 [tex]cm^{3}[/tex]
3. 30
Step-by-step explanation:
Area = [tex]\pi[/tex][tex]r^{2}[/tex]
= [tex]\pi[/tex] x [tex]10x^{2}[/tex]
= 100[tex]\pi[/tex]
Volume = l x w x h
= 3 x 3 x 3
= 27
For a long-distance person-to-person telephone call, a telephone company charges $ 0.72 for the first minute, $ 0.42 for each additional minute, and a $ 1.85 service charge. If the cost of a call is $ 8.03 comma how long did the person talk?
Answer:
13 mins
Step-by-step explanation:
8.03- 1.85= 6.18
-.72=5.46
/.42=13
What is the value of d21+d22+d23 given the matrix equation below?
Answer:
B. 8
Step-by-step explanation:
The question lacks the required diagram. Find the diagram in the attachment.
Before we can find d21, d22 and d23, we need to get the matrix D first as shown in the attached solution.
On comparison as shown in the attachment, d21 = 11, d22 = -10 and d23 = 7
Note that d21 refers to element in the second row and first column of the matrix
d22 is the element in the second row and second column of the matrix
d23 is the element in the second row and third column of the matrix
d21+d22+d23 = 11-10+7
d21+d22+d23 = 8
The second option is correct.
Do all perpendicular lines have negative reciprocal slopes?
Not necessarily, the more correct definition is opposite reciprocal slopes.
The example used is how horizontal and vertical lines are parallel. Horizontal lines have a slope of 0, also written as 0/1. However, vertical lines have an undefined slope, which isn't necessarily negative. It has a slope of 1/0, which is undefined. In this case, the reciprocal isn't negative.
In all other cases (1 and -1, 2 and -1/2, etc.) yes, the perpendicular pairs are negative and reciprocal.
The following crosstabulation summarizes the data for two categorical variables, x and y. The variable x can take on values low, medium, or high and the variable y can take on values yes or no.
Y
X Yes No Total
Low 20 10 30
Medium 15 35 50
High 20 5 25
Total 55 50 105
1. Compute the row percentage
2. Construct a sketch percentage of frequency bar chat with x on horozontal axis.
Answer:
Step-by-step explanation:
From the given data:
The row percentage can be determined by: taking each box in each row and by dividing it with its total on that line, after that we will multiply it by 100 to get the result of it's equivalent percentage.
Table reconstruct the table from the question ; we have:
y
x Yes No Total
Low 20 10 30
Medium 15 35 50
High 20 5 25
Total 55 50 105
For Low; the total on the row is 30 ;
so for Yes: we have 20/30 × 100 = 66.7
for No ; we have 10/30 × 100 = 33.3
For Medium ; the total on the row is 50 ;
so for Yes: we have 15/50 × 100 = 30
for No ; we have 35/50 × 100 = 70
For High ; the total on the row is 25;
so for Yes: we have 20/25 × 100 = 80
for No ; we have 5/25 × 100 = 20
y
x Yes No Total
Low 66.7 33.3 100
Medium 30 70 100
High 80 20 100
b. The construction of a sketch percentage of the frequency bar chat with x on horizontal axis is shown in the attached file below.
In a completely randomized design involving three treatments, the following information is provided: Treatment 1 Treatment 2 Treatment 3 Sample Size 5 10 5 Sample Mean 4 8 9 The overall mean for all the treatments is a. 7.00 b. 6.67 c. 7.25 d. 4.89
Answer:
c. 7.25
Step-by-step explanation:
Given the following information from an experiment:
[tex]\left\begin{array}{ccc}&$Sample Size&$Sample Mean \\$Treatment 1&5&4\\$Treatment 2&10&8\\$Treatment 3&5&9\end{array}\right[/tex]
Total Sample Size =5+10+5=20
Therefore, the overall mean
[tex]=\dfrac{(5 \times 4)+ (10 \times 8) + (5 \times 9)}{20} \\=\dfrac{145}{20}\\\\=7.25[/tex]
I don’t need you to explain just answer.
Answer: The answer is (x-5)^2
I NEED HELP PLEASE SOMEONE HELP ME
Answer:
2nd option is the correct answer
Step-by-step explanation:
3 times a number decreased by 6 is - 2
The population of bats in a large cave is 7000 and is growing exponentially at 14% per year. Write a function to represent the population of bats after
tt
t years, where the monthly rate of change can be found from a constant in the function.
Answer:
y=7000+14^t
Step-by-step explanation:
This equation shows that the original population of bats was 7000 and grows exponentially at a rate of 14% per year.
I put the graph below so you can see it.
In this exercise we have to identify how to write an exponential function from the data informed in the text, in this way we find that:
[tex]y=7000+14^t[/tex]
From the information given in the statement we find that:
The original population of bats was 7000Rate of 14% per year.Then writing this function as:
[tex]y=7000+14^t[/tex]
See more about function at brainly.com/question/5245372
(02.04 MC) Choose the equation that represents the line passing through the point (2, - 5) with a slope of −3. y = −3x − 13 y = −3x + 11 y = −3x + 13 y = −3x + 1
Answer:
it is b
Step-by-step explanation:
the answer is b because
The graph of g(x) = ax^2 opens downward and is narrower than the graph of f(x) = x^2. Which of the following could be the value of a?
The value of a should be less than -1.
Equation of parabola,The equation of a parabola is given by the following function,
[tex]y=f(x)=\pm a(x-h)^2+k[/tex]
where,
(h, k) denotes the coordinates of its vertex,
a defines how narrower is the parabola, and the "-" or "+" that the parabola will open up or down.
Given to us,[tex]f(x) = x^2[/tex]
[tex]g(x)=ax^2[/tex]
SolutionFor the parabola,g(x) to be narrower than the parabola f(x) the value of a should be less than 1. also for the parabola to open downward the value of a is needed to be negative.
Hence, the value of a should be less than -1.
Learn more about Equation of parabola:
https://brainly.com/question/4443998
Given AB intersects DE at point C. prove: DCB = ECA. What is the missing reason in step 5
Answer: the answer is linear pair
Step-by-step explanation:
Answer:
Linear pair postulate
Step-by-step explanation:
Please help! I don’t get what I’m supposed to put in those boxes
The volume of any cylinder is
V = pi*r^2*h
where r is the radius and h is the height. We are keeping r = 2 the same the entire time, as the first part of the instructions indicate. In contrast, h is allowed to vary or change based on the values shown in the table.
If h = 1, then,
V = pi*r^2*h
V = pi*2^2*1
V = pi*4
V = 4pi
So you'll write "4pi", without quotes of course, in the V column next to h = 1. This first row shows a height of 1 leads to a volume of 4pi.
-------------
Then if h = 2, we have,
V = pi*r^2*h
V = pi*2^2*2
V = pi*8
V = 8pi ... this is written in the second box
and finally if h = 3, we would say,
V = pi*r^2*h
V = pi*2^2*3
V = pi*12
V = 12pi .... and this is placed in the third box
---------------
The values of V we got were: 4pi, 8pi, 12pi
This is for h = 1,2 and 3 respectively in that order.
The sequence 4,8,12 is linear because we are adding 4 each time. More specifically, it fits the equation y = 4x where x = 1,2,3. Think of y = 4x as y = 4x+0 and that fits the slope intercept form y = mx+b.
i have a problem on statistics
5. Data on household vehicle miles of travel (VMT) are compiled annually by the Federal Highway Administration and are published in National Household Travel Survey, Summary of Travel Trends. Independent random samples of 15 midwestern households and 14 southern households provided the following data on last year’s VMT, in thousands of miles. At the 5% significance level, does there appear to be a difference in last year’s mean VMT for midwestern and southern households? Use both p-value and critical value approach. Assume population variance to be equal
Midwest
16.2 , 14.6 , 11.2 , 24.4 , 9.4 12.9 , 18.6 , 16.6 , 20.3 ,15.1 , 17.3 , 10.8 , 16.6 , 20.9 , 18.3
South
22.2, 19.2 , 9.3 , 24.6 ,20.2 , 15.8, 18.0 , 12.2 , 20.1 , 16.0 , 17.5 , 18.2 , 22.8 , 11.5
Answer:
Step-by-step explanation:
Hello!
The objective is to compare the VMT of mid western households and southwestern households. For this two independent random samples of households from both areas and their VMT were recorded:
Be
X₁: VMT of a mid western household
Midwest
16.2 , 14.6 , 11.2 , 24.4 , 9.4 12.9 , 18.6 , 16.6 , 20.3 ,15.1 , 17.3 , 10.8 , 16.6 , 20.9 , 18.3
n₁= 15
∑X₁= 243.20
∑X₁²= 4175.98
X[bar]₁= 16.21
S₁²= 16.64
S₁= 4.08
X₂: VMT of a southwestern household
22.2, 19.2 , 9.3 , 24.6 ,20.2 , 15.8, 18.0 , 12.2 , 20.1 , 16.0 , 17.5 , 18.2 , 22.8 , 11.5
n₂= 14
∑X₂= 247.60
∑X₂²= 4633.24
X[bar]₂= 17.69
S₂²= 19.56
S₂= 4.42
The parameters of study are the population means, if the claim is that the VMT of households is different in both areas, then you'd expect the population means to be different too.
The hypotheses are:
H₀: μ₁ = μ₂
H₁: μ₁ ≠ μ₂
α: 0.05
Assuming both populations are normal and since both population variances are equal the test to apply is an independent samples t test pooled variance:
[tex]t= \frac{(X[bar]_1-X[bar]2)-(Mu_1-Mu_2)}{Sa*\sqrt{\frac{1}{n_1} +\frac{1}{n_2} } } ~~t_{n_1+n_2-2}[/tex]
[tex]Sa^2= \frac{(n_1-1)S_1^2+(n_2-1)S_2^2}{n_1+n_2-2} = \frac{14*16.67+13*19.56}{15+14-2}= \frac{487.66}{27} = 18.06[/tex]
Sa= 4.249= 4.25
[tex]t_{H_0}= \frac{(16.21-17.69)-0}{4.25*\sqrt{\frac{1}{15} +\frac{1}{14} } }= -0.937= -0.94[/tex]
Critical value approach:
This test is two-tailed, this means that the rejection region is divided in two tails:
[tex]t_{n_1+n_2-2; \alpha /2}= t_{27; 0.025}= -2.052[/tex]
[tex]t_{n_1+n_2-2; 1-\alpha /2}= t_{27; 0.975}= 2.052[/tex]
The decision rule is:
If [tex]t_{H_0}[/tex] ≤ -2.052 or if [tex]t_{H_0}[/tex] ≥ 2.052, reject the null hypothesis.
If -2.052 < [tex]t_{H_0}[/tex] < 2.052, do not reject the null hypothesis.
The calculated value is within the "no rejection region" so the decision is to not reject the null hypothesis.
Using the p-value approach:
The p-value is the probability of obtaining a value as extreme as the calculated value of the statistic under the null hypothesis ([tex]t_{H_0}[/tex]). Just as the significance level, the p-value is two tailed, you can calculate it as:
P(t₂₇ ≤ -0.93) + P(t₂₇ ≥ 0.93)= P(t₂₇ ≤ -0.93) + (1 - P(t₂₇ < 0.93)= 0.1796 + ( 1 - 0.8204)= 0.1796*2= 0.3592
p-value= 0.3592
The p-value is always compared to the significance level, the decision rule for this approach is:
If the p-value ≤ α, reject the null hypothesis.
If the p-value > α, do not reject the null hypothesis.
The p-value is greater than α, so the decision is to not reject the null hypothesis.
At a 5% significance level, there is no significant evidence to reject the null hypothesis. You can conclude that the population means of the VMT for households of the Midwest South ers households.
I hope this mhelps!
There are 20 pieces of fruit in a bowl and 5 of them are apples. What percent of the fruit are apples?
Step-by-step explanation:
20fruits=100%
5fruits=?
5x100/20 5fruitsx5%
=24%
Here are three number cards.
The numbers are hidden.
?
?
?
The mode of the three numbers is 7.
The highest number is not 7.
The range is 4.
What are the three numbers? Write them in the boxes, from smallest to larges
O
INN
Answer:
7, 7, 11 are the three numbers.
Step-by-step explanation:
Given:
Mode of the three numbers = 7
Range of numbers i.e. difference between the smallest and the largest number is = 4
Value of highest number card [tex]\neq[/tex] 7
As per the definition of Mode:
Mode is the number that occurs the most number of times in the given set of numbers. In other words, mode is the number whose frequency is the highest in the given set of numbers.
Here, we have three numbers and mode is 7 that means 7 occurs at least two times in the three numbers.
Also, we are given that 7 is not highest number, plus 4 is the range that means 7 occurs exactly two times out of three numbers.
So, two numbers are 7 and 7.
7 is not highest and 4 is the range, so third number = 7+4 = 11
So, the numbers on the cards are 7, 7 and 11.
Will give Brainliest Talia took the bus from her home to the bank and then walked back to her home along the same route. The round trip took 0.9 hours total. The bus traveled at an average speed of 40 km/h and she walked at an average speed of 5 km/h. The rate of Trip 2 is blank km/h. The time of Trip 1 is blank hours.
Answer:
The rate of trip 2 is 5 km/h
The time of trip 1 is 0.9-x
Step-by-step explanation:
The rate of trip 2 is 5 km/h because it tells you she walked at an avg speed of 5 km/h.
The time of trip 1 is 0.9-x. It's because the time in trip 2 is x, and it says the total is 0.9. So just subtract 0.9-x.
Also I took the test on edge and attached a pic.
What is the value of X ? A-17 B-26 C-39 D-41
Answer:
D.
Step-by-step explanation:
It's a right triangle so
[tex]x^2=40^2+9^2[/tex]
x = 41
A university warehouse has received a shipment of 25 printers, of which 10 are laser printers and 15 are inkjet models. If 6 of these 25 are selected at random to be checked by a particular technician, what is the probability that exactly 3 of those selected are laser printers (so that the other 3 are inkjets)
Answer:
The probability is 0.31
Step-by-step explanation:
To find the probability, we will consider the following approach. Given a particular outcome, and considering that each outcome is equally likely, we can calculate the probability by simply counting the number of ways we get the desired outcome and divide it by the total number of outcomes.
In this case, the event of interest is choosing 3 laser printers and 3 inkjets. At first, we have a total of 25 printers and we will be choosing 6 printers at random. The total number of ways in which we can choose 6 elements out of 25 is [tex]\binom{25}{6}[/tex], where [tex]\binom{n}{k} = \frac{n!}{(n-k)!k!}[/tex]. We have that [tex]\binom{25}{6} = 177100[/tex]
Now, we will calculate the number of ways to which we obtain the desired event. We will be choosing 3 laser printers and 3 inkjets. So the total number of ways this can happen is the multiplication of the number of ways we can choose 3 printers out of 10 (for the laser printers) times the number of ways of choosing 3 printers out of 15 (for the inkjets). So, in this case, the event can be obtained in [tex]\binom{10}{3}\cdot \binom{15}{3} = 54600[/tex]
So the probability of having 3 laser printers and 3 inkjets is given by
[tex] \frac{54600}{177100} = \frac{78}{253} = 0.31[/tex]
The web publisher www.exploreiceland.is (Links to an external site.)Links to an external site. provides information on traveling to Iceland. Access to the website is free but revenues are generated by selling ads that are posted on the website. In the following month, the website has committed to displaying ads to 650,000 viewers, i.e., 650,000 impressions. Based on data from previous months the traffic to the website is estimated to be normally distributed with a mean of 850,000 viewers and a standard deviation of 150,000.
How many impressions should the web publisher have taken on, to be able to guarantee a 95% service level?
Answer:
1096750 impressions
Step-by-step explanation:
Given that :
Mean = 850,000
Standard deviation = 150,000
If we assume that X should be the numbers of impressions created;
Then ;
[tex]X \approx N (\mu , \sigma^2)[/tex]
Now ; representing x as the value for the number of impression needed ; Then ;
[tex]P(X>x) = 0.95[/tex]
[tex]P(\dfrac{X- \mu}{\sigma} > \dfrac{x -850000}{150000}) = 0.95[/tex]
[tex]P(Z> \dfrac{ x -850000}{150000}) = 0.95[/tex]
From normal tables:
[tex]P(Z >1.645) = 0.95[/tex]
[tex]\dfrac{x - 850000}{150000} =1.645[/tex]
(x- 850000) = 1.645(150000)
x - 850000 = 246750
x = 246750 + 850000
x = 1096750 impressions
Suppose that a researcher is planning a new study on hemoglobin levels amongst women under 25 years old. Previous research suggest that the standard deviation of hemoglobin is 0.7 g/dl. In the new study the research wants to have the standard error for the sample mean to be no more than 0.05 g/dl. Find the required sample size for the new study.
Answer:
A sample size of at least 531 is required.
Step-by-step explanation:
We are lacking the confidence level to solve this question, so i am going to use a 90% confidence level.
We have that to find our [tex]\alpha[/tex] level, that is the subtraction of 1 by the confidence interval divided by 2. So:
[tex]\alpha = \frac{1-0.9}{2} = 0.05[/tex]
Now, we have to find z in the Ztable as such z has a pvalue of [tex]1-\alpha[/tex].
So it is z with a pvalue of [tex]1-0.05 = 0.95[/tex], so [tex]z = 1.645[/tex]
Now, find the margin of error M as such
[tex]M = z*\frac{\sigma}{\sqrt{n}}[/tex]
In which [tex]\sigma[/tex] is the standard deviation of the population and n is the size of the sample.
Find the required sample size for the new study.
A sample size of at least n is required.
n is found when [tex]M = 0.05[/tex]
We have that [tex]\sigma = 0.7[/tex]
So
[tex]M = z*\frac{\sigma}{\sqrt{n}}[/tex]
[tex]0.05 = 1.645*\frac{0.7}{\sqrt{n}}[/tex]
[tex]0.05\sqrt{n} = 1.645*0.7[/tex]
[tex]\sqrt{n} = \frac{1.645*0.7}{0.05}[/tex]
[tex](\sqrt{n})^{2} = (\frac{1.645*0.7}{0.05})^{2}[/tex]
[tex]n = 530.4[/tex]
Rounding up
A sample size of at least 531 is required.
