Answer:
b. external validity
Step-by-step explanation:
External Validity is the applicability of the results of an experiment to the real world. Most times, there are threats to the validity of an experiment which could result in little or no effect on the general population. For example, if the method of selection reflects a measure of bias, then this could affect the result. Also if the participants are taking different aspects of the same test, it could also affect its validity as they may not be able to make a correct conclusion. If the sample size is not reflective of the entire population, it could also pose a threat to the validity of the experiment.
John's experiment is weak in its external validity because it cannot be generalized to the entire population of customers. He has to identify the threats to the validity of his experiment and correct them. For example, the sample selection may be biased.
A laptop producing company also produces laptop batteries, and claims that the batteries
it produces power a laptop for about 4:00 hours. But, you doubted the claim and collected
data from 500 laptop users of the same brand and battery, and you found out the battery
powers the laptop for about 3:00 hours and 30 minutes. Considering an alpha of 0.05,
prove the claim of the company is true or false or show whether you accept the
company’s claim or reject it? Please also write H0 and Ha statements for testing your
hypothesis
Answer:
There is enough evidence to support the claim that the batteries power the laptops for significantly less than 4 hours. (P-value = 0).
The null and alternative hypothesis are:
[tex]H_0: \mu=4\\\\H_a:\mu< 4[/tex]
Step-by-step explanation:
The question is incomplete: To test this claim a sample or population standard deviation is needed.
We will estimate that the sample standard deviation is 2 hours, and use a t-test to test that claim.
NOTE (after solving): The difference between the sample mean and the mean of the null hypothesis is big enough to reject the null hypothesis, even when we have a sample standard deviation of 3.5 hours, which can be considered bigger than the maximum standard deviation for the sample.
This is a hypothesis test for the population mean.
The claim is that the batteries power the laptops for significantly less than 4 hours.
Then, the null and alternative hypothesis are:
[tex]H_0: \mu=4\\\\H_a:\mu< 4[/tex]
The significance level is 0.05.
The sample has a size n=500.
The sample mean is M=3.5.
As the standard deviation of the population is not known, we estimate it with the sample standard deviation, that has a value of s=2.
The estimated standard error of the mean is computed using the formula:
[tex]s_M=\dfrac{s}{\sqrt{n}}=\dfrac{2}{\sqrt{500}}=0.0894[/tex]
Then, we can calculate the t-statistic as:
[tex]t=\dfrac{M-\mu}{s/\sqrt{n}}=\dfrac{3.5-4}{0.0894}=\dfrac{-0.5}{0.0894}=-5.5902[/tex]
The degrees of freedom for this sample size are:
[tex]df=n-1=500-1=499[/tex]
This test is a left-tailed test, with 499 degrees of freedom and t=-5.5902, so the P-value for this test is calculated as (using a t-table):
[tex]P-value=P(t<-5.5902)=0[/tex]
As the P-value (0) is smaller than the significance level (0.05), the effect is significant.
The null hypothesis is rejected.
There is enough evidence to support the claim that the batteries power the laptops for significantly less than 4 hours.
Which statements are true?
If all angles of a quadrilateral are right angles, then the quadrilateral must be a square.
Two shapes are similar if and only if their corresponding angles are equal.
All quadrilaterals have four sides, and the sum of all angles in a quadrilateral is 180º.
if the diagonals of a quadrilateral are perpendicular bisectors, then the quadrilateral must be a rhombus.
There are three vertices in a triangle, or there are four sides in a pentagon.
Any two triangles are either similar or congruent.
Answer:
Step-by-step explanation:
1) If all angles of a quadrilateral are right angles, then the quadrilateral must be a square. This is not true because the quadrilateral can also be a rectangle.
2) Two shapes are similar if and only if their corresponding angles are equal. This is true.
3) All quadrilaterals have four sides, and the sum of all angles in a quadrilateral is 180º. This is false because the sum of the angles is 360°
4) if the diagonals of a quadrilateral are perpendicular bisectors, then the quadrilateral must be a rhombus. This is true.
5) There are three vertices in a triangle, or there are four sides in a pentagon. This is false because a Pentagon has 5 sides.
6) Any two triangles are either similar or congruent. This is not true. Congruent triangles are always similar
Therefore, the true statements are 2 and 4
Answer:
its B and D
Step-by-step explanation:
A humanities professor assigns letter grades on a test according to the following scheme. A: Top 12% of scores B: Scores below the top 12% and above the bottom 61% C: Scores below the top 39% and above the bottom 21% D: Scores below the top 79% and above the bottom 6% F: Bottom 6% of scores Scores on the test are normally distributed with a mean of 67.7 and a standard deviation of 7.8. Find the minimum score required for an A grade. Round your answer to the nearest whole number, if necessary.
Answer:
The minimum score required for an A grade is 77.
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 = 67.7, \sigma = 7.8[/tex]
Find the minimum score required for an A grade.
Top 12% of scores get an A.
100-12 = 88th percentile.
The 88th percentile of scores is the minimum required for an A grade. This score is X when Z has a pvalue of 0.88. So X when Z = 1.175.
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]1.175 = \frac{X - 67.7}{7.8}[/tex]
[tex]X - 67.7 = 7.8*1.175[/tex]
[tex]X = 76.865[/tex]
Rounding to the nearest whole number:
The minimum score required for an A grade is 77.
Assuming that $3u + 12v\neq0$, simplify $\dfrac{12u^3 + 48u^2v}{3u+12v}$.
Answer:
4u²
Step-by-step explanation:
[tex]\dfrac{12u^3 + 48u^2v}{3u+12v}=\dfrac{12u^2(u+4v)}{3(u+4v)}=\boxed{4u^2}[/tex]
Common factors cancel from numerator and denominator. The one factor that might make the expression undefined is given as non-zero, so no additional restrictions apply.
Help asap giving branlist!!!
Answer:
B
Step-by-step explanation:
Let's arrange it into slope-intercept form.
2x - y = 4
y = 2x - 4
We are looking for a line with slope of 2 and y-intercept -4. This line is Line B.
Write the standard form of the line that passes through the given points. Inclide your work in the final answer. Type your answer in the box provided or use the upload option to submit your solution. (4,7) and (0,7)
Answer:
y=7
Step-by-step explanation:
Slope: 7-7/4-0=0
Point: (0,7)
pt/slope form:
y-7=(0)(x-0)
y=7
Which is an irrational number?
Answer: THE SECOND ONE
Step-by-step explanation:
Answer: the second one
Step-by-step explanation:
Is f(x) continuous at x equals 4? Why or why not? A. No, f(x) is not continuous at x equals 4 because ModifyingBelow lim With x right arrow 4 f (x )does not exist. B. Yes, f(x) is continuous at x equals 4 because f (4 )exists. C. No, f(x) is not continuous at x equals 4 because f (4 )is undefined. D. Yes, f(x) is continuous at x equals 4 because ModifyingBelow lim With x right arrow 4 f (x )equals f (4 ).
Corrected Question
Is the function given by:
[tex]f(x)=\left\{\begin{array}{ccc}\frac{1}{4}x+1 &x\leq 4\\4x-11&x>4\end{array}\right[/tex]
continuous at x=4? Why or why not? Choose the correct answer below.
Answer:
(D) Yes, f(x) is continuous at x = 4 because [tex]Lim_{x \to 4}f(x)=f(4)[/tex]
Step-by-step explanation:
Given the function:
[tex]f(x)=\left\{\begin{array}{ccc}\frac{1}{4}x+1 &x\leq 4\\4x-11&x>4\end{array}\right[/tex]
A function to be continuous at some value c in its domain if the following condition holds:
f(c) exists and is defined.[tex]Lim_{x \to c}$ f(x)[/tex] exists. [tex]f(c)=Lim_{x \to c}$ f(x)[/tex]At x=4
[tex]f(4)=\dfrac{1}{4}*4+1=2[/tex][tex]Lim_{x \to 4}f(x)=2[/tex]Therefore: [tex]Lim_{x \to 4}f(x)=f(4)=2[/tex]
By the above, the function satisfies the condition for continuity.
The correct option is D.
Which side will require the use of the distance formula to find the length?
Answer:
CD
Step-by-step explanation:
For all sides except CD, you do not need the distance formula, since they are vertical or horizontal, meaning that you can find their length simply through subtraction. However, with side CD, since it is diagonal, you need to form a right triangle with to solve its length. Hope this helps!
A.13.4 feet
B.13.1 feet
C.18 feet
D.10.4 feet
Answer:
13.4 feet
Step-by-step explanation:
use physagorean law
√12²+6²=cable
=13.4 feet
Use the area to find the radius. If you could include steps that’ll be very helpful :)
Answer:
Radius = 13 m
Step-by-step explanation:
Formula for area of circle is given as:
[tex]A = \pi {r}^{2} \\ \\ \therefore \: 169\pi \: = \pi {r}^{2} \\ \\ \therefore \: {r}^{2} = \frac{169\pi }{\pi} \\ \\ \therefore \: {r}^{2} = 169 \\ \\ \therefore \: {r} = \pm \sqrt{169} \\ \\\therefore \: r = \pm \: 13 \: m \\ \\ \because \: radius \: of \: a \: circle \: can \: not \: be \: a \: negative \: \\quantity \\ \\ \huge \red{ \boxed{\therefore \: r = 13 \: m }}[/tex]
Suppose that a random sample of adult males has a sample mean heart mass of x¯=310.1 grams, with a sample standard deviation of s=6.6 grams. Since adult male heart masses are generally symmetric and bell-shaped, we can apply the Empirical Rule. Between what two masses do approximately 68% of the data occur? Round your answer to the nearest tenth.
Answer:
Between 303.5 grams and 316.7 grams
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 310.1 grams
Standard deviation = 6.6 grams
Between what two masses do approximately 68% of the data occur?
By the Empirical Rule, within 1 standard deviation of the mean.
310.1 - 6.6 = 303.5 grams
310.1 + 6.6 = 316.7 grams
Between 303.5 grams and 316.7 grams
Mai deposited $4000 into an account with 4.8% interest, compounded quarterly. Assuming that no withdrawals are made, how much will she have in the
account after 7 years?
Do not round any intermediate computations, and round your answer to the nearest cent.
Answer:
5,586.17
Step-by-step explanation:
A = $ 5,586.17
A = P + I where
P (principal) = $ 4,000.00
I (interest) = $ 1,586.17
Compound Interest Equation
A = P(1 + r/n)^nt
Where:
A = Accrued Amount (principal + interest)
P = Principal Amount
I = Interest Amount
R = Annual Nominal Interest Rate in percent
r = Annual Nominal Interest Rate as a decimal
r = R/100
t = Time Involved in years, 0.5 years is calculated as 6 months, etc.
n = number of compounding periods per unit t; at the END of each period
1.solve for x 3x - 2 = 3 - 4x
Answer:
[tex]x=\frac{5}{7}[/tex]
Step-by-step explanation:
[tex]3x - 2 = 3 - 4x[/tex]
Add [tex]2[/tex] and [tex]4x[/tex] on both sides of the equation.
[tex]3x - 2 +2+4x= 3 - 4x+2+4x[/tex]
[tex]3x+4x=-4x+5+4x[/tex]
[tex]7x=5[/tex]
Divide [tex]7[/tex] on both sides of the equation.
[tex]\frac{7x}{7}=\frac{5}{7}[/tex]
[tex]x=\frac{5}{7}[/tex]
What is the image of R for a dilation with center (0,0) and a scale factor of 1 1/2?
Answer: The image is (6,-3)
Step-by-step explanation:
The coordinates of R is ( 4,-2) and to find the image using the scale factor 1.5 you will multiply the x coordinates by 1.5 and the y coordinate also by 1.5 to have the new image of R.
4 * 1.5 = 6
-2 * 1.5 = -3
The new coordinates care (6, -3)
The hypotenuse of a right triangle is 95 inches long. One leg is 4 inch(es) longer than the other. Find the lengths of the legs of the triangle. Round your answers to the nearest tenth of an inch.
Answer:
65.1 and 69.1
Step-by-step explanation:
a^2+b^2=c^2
c=95
b=a+4
Solve for a^2+(a+4)^2=95^2
a=65.1
b=a+4=69.1
Answer:
65.1 and 69.1
Step-by-step explanation:
c² = a² + b²
c= 95
a - one leg
b= (a + 4) - second leg
95² = a² + (a + 4)²
9025 = a² + a² + 2*4a + 16
2a² + 8a - 9009 = 0
[tex]a= \frac{-b +/-\sqrt{b^2 - 4ac} }{2a} \\\\a = \frac{-8 +/-\sqrt{8^2 - 4*2*9009} }{2*2} \\\\a=65.1 \ and \ a=- 69.1[/tex]
A leg length can be only positive. a = 65.1
b = 65.1 + 4 = 69.1
A fluctuating electric current II may be considered a uniformly distributed random variable over the interval (9, 11)(9,11). If this current flows through a 2-ohm resistor, find the probability density function of the power P = 2I^2P=2I 2 .
Answer:
Step-by-step explanation:
A fluctuating electric current II may be considered a uniformly distributed random variable over the interval (9, 11)
[tex]p_1=\{^{\frac{1}{2}:9\leq i\leq 11}_{0:otherwise[/tex]
Now define
[tex]p = 2I^2[/tex]
[tex]\Rightarrow I^2=(\frac{p}{2} )\\\\\Rightarrow I=(\frac{p}{2} )^{\frac{1}{2} }\\\\\Rightarrow h^{-1}(p)=(\frac{p}{2} )^{\frac{1}{2}}[/tex]
[tex]\frac{dh^{-1}}{dp} =\frac{d[h^{-1}(p)]}{dp} \\\\=\frac{d(p/2)^{\frac{1}{2} }}{dp}[/tex]
[tex]=\frac{1}{2} \times \frac{1}{2} (\frac{p}{2} )^{{\frac{1}{2}-1} }\\\\=\frac{1}{4}(\frac{p}{2} )^{{\frac{1}{2}-1} }\\\\=\frac{1}{2}(\frac{2}{p} )^{{\frac{1}{2}} }[/tex]
using the transformation method, we get
[tex]f_p(p)=f_1(h^{-1}(p))|\frac{d[h^{-1}(p)]}{dp} |\\\\=\frac{1}{2} \times \frac{1}{4} (\frac{2}{p} )^{\frac{1}{2} }\\\\=\frac{1}{8} (\frac{2}{p} )^{\frac{1}{2} }[/tex]
[tex]f_p(p)=\{^{\frac{1}{8} (\frac{2}{p} )^{\frac{1}{2} },162\leqp\leq 242} }_{0,otherwise}[/tex]
y=5•(0)
Which graph represents the function
?
a triangle has an area of 15 cm. a similar triangle is drawn using a scale factor of 3.5. what is the area of the similar triangle to the nearest square cm?
Answer:
184 square cm
Step-by-step explanation:
The ratio of areas is the square of the ratio of the scale factor. The larger triangle has an area of ...
(15 cm²)(3.5²) = 183.75 cm²
The area of the similar triangle is about 184 cm².
Which equation can be used to determine the distance between the origin and (–2, –4)? d = StartRoot ((0 minus 2) + (0 minus 4)) squared EndRoot d = StartRoot (0 minus (negative 2)) squared + (0 minus (negative 4)) squared EndRoot d = StartRoot ((0 minus 2) minus (0 minus 4)) squared EndRoot d = StartRoot (0 minus (negative 2)) squared minus (0 minus (negative 4)) squared EndRoot
Answer:person up top is right it’s B
Step-by-step explanation: on edg 2020
Answer:
The answer is B
Step-by-step explanation:
lol yw guys
find ∠AEC in the figure below.
Answer:
C. 105°
Step-by-step explanation:
Angles BED and CED are supplementary, so ...
(2y +x) +(-2y +3x) = 180
4x = 180
2x = 90
Substituting this into the expression for angle AEB, we have ...
Angle AEB = (90 -15)° = 75°
Angle AEC is the supplement to that, so is ...
∠AEC = 180° -75° = 105° . . . . . matches choice C
Answer: C. 105
Step-by-step explanation:
Adding BED and DEC for being adjacent angles we obtain:
[tex]2y+x +-2y+3x = 180\\4x = 180\\x=45\\[/tex]
Substituting x in BEA
[tex]BEA=2(45)-15=75[/tex]
Adding BEA and AEC for being adjacent angles we obtain:
[tex]BEA+AEC=180\\AEC=180-BEA\\AEC=180-75\\AEC=105[/tex]
Select the linear function that describes the relationship between the domain and
range in the table below.
x fx)
-15
03
1 1
The linear function that describes the table is f(x) = -2x + 3
How to find linear function?The linear function of an equation can be found as follows:
y = mx + b
where
m = slopeb = y-interceptTherefore, using the table
b = 3
using (1, 1)
1 = m + 3
m = -2
Therefore, the function that represent the table is as follows:
f(x) = -2x + 3
learn more on linear function here: https://brainly.com/question/16911425
#SPJ1
Answer: f(x) = -2x + 3
Step-by-step explanation:
What is the y-intercept of a line that has a slope of -3 and passes through point (0, -7)?
Answer:
Step-by-step explanation:
line equation: y=mx + C
substitute given values
-7 = -3*0 + C
C=y= -7 ANS
Consider the relation S(x, y) : x is a brother or sister of y on the set, H, of living humans. (For the purposes of this problem, a sibling of a person means another person with the same two parents, so don’t consider half siblings.) Determine which of the three properties, reflexive, symmetric, transitive, hold for the relation S (explain your three answers). Is S an equivalence relation on H?
Answer:
- Not reflexive
- Symmetric
- Transitive
Step-by-step explanation:
- A person is not a sibling of himself so the relation is NOT reflexive
- If a person is a sibling of an other person, the other person is a sibling of the person. Therefore the relation is SYMMETRIC
- If a person A is a sibling of B, and a person B is a sibling of C then, person A is a sibling of person C. Therefore the relation is TRANSITIVE.
A marine biologist is preparing a deep-sea submersible for a dive. The sub stores breathing air under high pressure in a spherical air tank that measures wide. The biologist estimates she will need of air for the dive. Calculate the pressure to which this volume of air must be compressed in order to fit into the air tank. Write your answer in atmospheres. Round your answer to significant digits.
The complete question is;
A marine biologist is preparing a deep-sea submersible for a dive. The sub stores breathing air under high pressure in a spherical air tank that measures 78.0 cm wide. The biologist estimates she will need 2600 L of air for the dive. Calculate the pressure to which this volume of air must be compressed in order to fit in to the air tank. Write you answer in atmospheres
Answer:
10.5 atm
Step-by-step explanation:
Formula for Volume of a sphere is;
V = (4/3)πr³
r = 78/2 = 39 cm
V = (4/3)π(39)³
V = (4/3)*π*59319
V = 248475 cm³
Now, from conversions, 1000 cm³ = 1L
So,
V = 248475/1000
V = 248.5 L
This is the volume of the storage tank
If we assume that the 2600 L of air is measured at 1 atmosphere pressure, then we will obtain the following relationship:
From Boyles law,
P1 × V1 = P2 × V2
Thus;
(1 atm) × (2600 L) = (P2) × (248.5 L)
P2 = 2600/248.5
P2 = 10.463 atmospheres
Approximating to 3 significant figures is; P2 = 10.5 atm
A farmer knows that every 50 eggs his chickens lay, only 45 will be marketable. If his
chickens lay 1000 eggs in a week, how many of them will be marketable?
Answer:
900 eggs
Step-by-step explanation:
45/50 are marketable
divide the top and bottom by 5
9/10
Multiply this fraction by the 1000 eggs laid
9/10 *1000
900 eggs will be marketable
Answer:
900
Step-by-step explanation:
Patrick’s luck had changed over night – but not his skill at mathematical reasoning. The day after graduating from college he used the $20 that his grandmother had given him as a graduation gift to buy a lottery ticket. He knew his chances of winning the lottery were extremely low and it probably was not a good way to spend this money. But he also remembered from the class he took in business analytics that bad decisions some-times result in good outcomes. So he said to himself, "What the heck? Maybe this bad decision will be the one with a good outcome." And with that thought, he bought his lottery ticket.The next day Patrick pulled the crumpled lottery ticket out of the back pocket of his bluejeans and tried to compare his numbers to the winning numbers printed in the paper. When his eyes finally came into focus on the numbers they also just about popped out of his head. He had a winning ticket! In the ensuing days he learned that his share of the jackpot would give him a lump sum payout of about $500,000 after taxes. He knew what he was going to do with part of the money, buy a new car, pay off his college loans, and send his grandmother on an all expenses paid trip to Hawaii. But he also knew that he couldn’t continue to hope for good outcomes to arise from more bad decisions. So he decided to take half of his winnings and invest it for his retirement. So what do you think? Who is right, Josh or Peyton? And more important, why?
Answer:
I assume Josh and Peyton are his friends and both gave him advice on what to do with half of the money from the big lottery win.
Let's say Josh said "save it or invest it for your retirement" and Peyton said "use it to keep playing the lottery.
We will now look at the sense in each piece of advice!
Step-by-step explanation:
JOSH
By investing the $250,000 (half of the money won), Patrick will be sure that the money is available for him anytime and would even have gotten interest, by the time he's ready to use it.
PEYTON
By playing the lottery continuously, Patrick could get lucky once in a while and win big again. How big though?
Analyzing with the figures given,
$20 gets Patrick a lottery ticket.
$250,000 will get him 12,500 lottery tickets!
Whether he's buying the tickets at once or he'll play the lottery once in a while, I'll say he has good chances of winning big again.
So if the probability of winning big after purchasing up to 12,500 tickets is close to 1, Patrick should play the lottery with the $250,000
If the probability of winning big after purchasing 12,500 lottery tickets is close to 0 (closer to 0 than it is to 1) then Patrick should invest the $250,000 in retirement.
A tree diagram is simply a way of representing a sequence of events. True or False.
Answer:
True.
Step-by-step explanation:
A tree diagram is a diagram used in general mathematics, statistics, and probability to show a sequence of events. This tool is used to calculate the number of possibilities of an event to occur. Commonly, the tool of a tree diagram is used to find the possibility of outcome while flipping a coin. It is a diagram in which connections between the events is shown using the strucure of branching connecting lines.
So, the given statement is true, that is a simple way of showing events in a sequence.
What is the approximate value of sin B?
B
>
17.46
7
A
16
Answer:
Option (B)
Step-by-step explanation:
From the figure attached,
AB = 7 units
BC = 17.46 units
AC = 16 units
Now we apply the sine rule in the given triangle ABC,
SinB = [tex]\frac{\text{Opposite side}}{\text{Hypotenuse}}[/tex]
= [tex]\frac{AC}{BC}[/tex]
= [tex]\frac{16}{17.46}[/tex]
= 0.916
≈ 0.92
Therefore, Option (B) will be the answer.
Answer:
DIFFERENT PICS
Step-by-step explanation:
I had one and the awnser was 0.40, and C had a arch whereas B did not.
The length and with of a rectangle are consecutive odd integers . The perimeter is 104 meters .find the length and with
Answer:
25 m, 27 m
Step-by-step explanation:
The perimeter is twice the sum of length and width, so that sum is 52 m. Half that is the average of length and width, so will be the even integer between the two consecutive odd integers.
52/2 = 26
The length and width are 25 m and 27 m.
