AnswersMathematics III AHypothesis Testing

Hypothesis Testing — Unit test Answers

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The histogram below shows the estimated monthly salaries of company employees with different years of experience. How might the graph be misleading?

Question illustration
T
The scale on the y-axis overemphasizes the difference in salaries between different experience levels.
T
The scale on the y-axis underemphasizes the difference in salaries between different experience levels.
T
The scale on the x-axis overemphasizes the difference in salaries between different experience levels.
T
The scale on the x-axis underemphasizes the difference in salaries between different experience levels.
2
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The president of the math club is conducting a survey to see where the twelfth-grade class wants to go on their field trip. Instead of asking the whole class, she surveys only the twelfth-grade members of the math club. She records their choices and plans to present the results to the school principal. What type of sampling did she use?

A
systematic random sampling
B
simple random sampling
C
stratified sampling
D
convenience sampling
3

A city’s annual rainfall totals are normally distributed, and the probability that the city gets more than 43.2 inches of rain in a year is given by . If the standard deviation of the city’s yearly rainfall totals is 1.8 inches, what is the city’s mean annual rainfall?

Question illustration
A
40.5 inches
B
41.4 inches
C
45.0 inches
D
45.9 inches
4

Which set of population data is the least dispersed from its mean?

A
2, 3, 2, 9
B
4, 0, 4, 0
C
6, 2, 2, 2
D
9, 3, 5, 3
5

A utility company hires pollsters to knock on random doors in different parts of town to survey residents about the cost of their electric bill. Would this study be biased? Why or why not?

A
No, it is not biased. All residents of the town will have the opportunity to respond.
B
Yes, it is biased. Some of the residents who are surveyed may not want to respond to someone who knocks at their door.
C
No, it is not biased. All residents who are surveyed will want to respond.
D
Yes, it is biased. Only certain parts of the town were surveyed.
6

Opal is collecting data on water levels in different parts of town. She notices that her sample data has a low-value outlier. Which statement must be true?

A
Removing the outlier will not change the spread of the graph of the data set.
B
Removing the outlier will not change the variance of the data set.
C
Removing the outlier will increase the variance of the data set.
D
Removing the outlier will decrease the spread of the graph of the data set.
7

Weston completed a hypothesis test and found that he could not reject the null hypothesis. Which of the following is a valid reason for his conclusion?

A
The z-statistic is less than 0.
B
The z-statistic lies in the critical region.
C
The z-statistic is greater than 0.
D
The z-statistic lies outside the critical region.
8

The proportions of multiple samples of registered voters who vote are normally distributed, with a mean proportion of 0.38 and a standard deviation of 0.0485. What is the probability that a sample chosen at random has a proportion of registered voters who vote between 0.37 and 0.39? Use the portion of the standard normal table below to help answer the question.zProbability0.000.50000.040.51600.210.58320.370.64430.380.64810.390.65171.000.8413

A
2%
B
17%
C
58%
D
65%
9

A researcher wants to survey people from different age groups to analyze voting patterns. Which type of survey will best accomplish this goal?

A
systematic random sampling
B
voluntary sampling
C
convenience sampling
D
stratified sampling
10

The distribution of the values of a population is shown below, and a simple random sample is drawn from the population. Based on this information alone, can the sample be used to make inferences about the population?

Question illustration
A
No, because the population values appear to be normally distributed.
B
No, because the population values do not appear to be normally distributed.
C
Yes, because the population values appear to be normally distributed.
D
Yes, because the population values do not appear to be normally distributed.
11

Car insurance companies want to keep track of the average cost per claim. The current data in use for Auto Insurance R Us is an average of $2,200 for each claim with a standard deviation of $500. With this average, the company can stay competitive with rates but not lose money. However, the statistician for the company believes that the cost of the average claim has increased. He pulled 40 recent claims and found the average to be $2,350. Which most restrictive level of significance would suggest that the company should raise rates? Upper-Tail Valuesa5%2.5%1%Critical z-values1.651.962.58

A
1%
B
2.5%
C
5%
D
10%
12

Voluntary sampling is one type of sampling method that is not probability based. This means that

A
each member of a population is equally likely to be chosen for the survey.
B
the results of the survey cannot reliably be extended and generalized.
C
the likelihood of a member of the population volunteering to be surveyed is not probable.
D
the results of the survey are not mathematically probable.
13

What is the formula for margin of error?

A
ME =
Option A
B
ME =
Option B
C
ME =
Option C
D
ME =
Option D
14

The life spans of a computer manufacturer’s hard drives are normally distributed, with a mean of 3 years 6 months and a standard deviation of 9 months. What is the probability of a randomly selected hard drive from the company lasting between 2 years 3 months and 3 years 3 months? Use the portion of the standard normal table below to help answer the question.zProbability0.000.50000.230.59100.330.62930.670.74861.000.84131.330.90821.670.95252.000.9772

A
32%
B
37%
C
42%
D
95%
15

When finding the margin of error for the mean of a normally distributed population from a sample, what is , assuming a confidence level of 74%?

Question illustration
A
0.13
B
0.26
C
0.74
D
0.87

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