Question 6(1 point)

Suppose you are a civil engineer, specializing in traffic volume control for the City of Grand Rapids. Your department has been receiving a multitude of complaints about traffic wait times for a certain intersection in the heart of downtown. To see if these claims are valid, you want to monitor the true average wait time at that intersection. Over the course of a few months, you record the average number of minutes a car waits at the intersection between 4:00 PM and 5:00 PM. With a sample size of 10 cars, the average wait time is 7.21 minutes with a standard deviation of 1.6012 minutes. Construct a 99% confidence interval for the true average wait time for a car at the intersection between 4:00 PM and 5:00 PM.

Question 6 options:

1)

( -5.564 , 8.856 )

2)

( 6.704 , 7.716 )

3)

( 5.605 , 8.815 )

4)

( 5.564 , 8.856 )

5)

( 3.96 , 10.46 )

Question 7(1 point)

The owner of a local supermarket believes the average number of gallons of milk the store sells per day is 197.3. In a random sample of 25 days, the owner finds that the average number of gallons sold was 205.9 with a standard deviation of 37.28. Using this information, the owner calculated the confidence interval of (190.5, 221.3) with a confidence level of 95%. Which of the following statements is the best conclusion?

Question 7 options:

1)

We cannot determine the proper interpretation based on the information given.

2)

We are 95% confident that the average number of gallons sold per day is less than 197.3.

3)

The percentage of days on which more than 197.3 gallons of milk are sold is 95%.

4)

The average number of gallons sold per day is not signficantly different from 197.3.

5)

We are 95% confident that the average number of gallons sold per day is greater than 197.3.

Question 8(1 point)

It is believed that using a solid state drive (SSD) in a computer results in faster boot times when compared to a computer with a traditional hard disk (HDD). You sample a group of computers and use the sample statistics to calculate a 90% confidence interval of (-6.53, 1.17). This interval estimates the difference of (average boot time (HDD) - average boot time (SSD)). What can we conclude from this interval?

Question 8 options:

1)

There is no significant difference between the average boot time for a computer with an SSD drive and one with an HDD drive at 90% confidence.

2)

We do not have enough information to make a conclusion.

3)

We are 90% confident that the average boot time of all computers with an SSD is greater than the average of all computers with an HDD.

4)

We are 90% confident that the average boot time of all computers with an HDD is greater than the average of all computers with an SSD.

5)

We are 90% confident that the difference between the two sample means falls within the interval.

Question 9(1 point)

The owner of a golf course wants to determine if his golf course is more difficult than the one his friend owns. He has 8 golfers play a round of 18 holes on his golf course and records their scores. Later that week, he has the same 8 golfers play a round of golf on his friend's course and records their scores again. The average difference in the scores (treated as the scores on his course - the scores on his friend's course) is 7.19 and the standard deviation of the differences is 17.7487. Calculate a 90% confidence interval to estimate the average difference in scores between the two courses.

Question 9 options:

1)

(-4.6987, 19.0787)

2)

(5.2954, 9.0846)

3)

(4.6987, 19.0787)

4)

(-4.4789, 18.8589)

5)

(0.9149, 13.4651)

Question 10(1 point)

A student at a university wants to determine if the proportion of students that use iPhones is greater than 0.42. If the student conducts a hypothesis test, what will the null and alternative hypotheses be?

Question 10 options:

1)

H_O: p 0.42

H_A: p < 0.42

2)

H_O: p = 0.42

H_A: p 0.42

3)

H_O: p < 0.42

H_A: p 0.42

4)

H_O: p > 0.42

H_A: p 0.42

5)

H_O: p 0.42

H_A: p > 0.42

Question 11(1 point)

Your friend tells you that the proportion of active Major League Baseball players who have a batting average greater than .300 is different from 0.62, a claim you would like to test. The hypotheses for this test are Null Hypothesis: p = 0.62, Alternative Hypothesis: p 0.62. If you randomly sample 22 players and determine that 12 of them have a batting average higher than .300, what is the test statistic and p-value?

Question 11 options:

1)

Test Statistic: -0.72, P-Value: 0.764

2)

Test Statistic: 0.72, P-Value: 0.471

3)

Test Statistic: -0.72, P-Value: 0.529

4)

Test Statistic: -0.72, P-Value: 0.471

5)

Test Statistic: -0.72, P-Value: 0.236

Question 12(1 point)

Consumers Energy states that the average electric bill across the state is $113.66. You want to test the claim that the average bill amount is actually greater than $113.66. The hypotheses for this situation are as follows: Null Hypothesis: 113.66, Alternative Hypothesis: > 113.66. You complete a randomized survey throughout the state and perform a one-sample hypothesis test for the mean, which results in a p-value of 0.0429. What is the appropriate conclusion? Conclude at the 5% level of significance.

Question 12 options:

1)

The true average electric bill is significantly less than $113.66.

2)

We did not find enough evidence to say the true average electric bill is greater than $113.66.

3)

The true average electric bill is significantly different from $113.66.

4)

The true average electric bill is significantly greater than $113.66.

5)

The true average electric bill is less than or equal to $113.66.

Question 13(1 point)

Does the average internet speed of an ISP depend on continent? Specifically, you would like to test whether customers in North America have an average internet download speed that is different from the average download speed of customers in Europe. If North American customers are in group 1 and European customers are in group 2, what are the hypotheses for your test of interest?

Question 13 options:

1)

H_O: _{1 2}

H_A: ₁< ₂

2)

H_O: ₁> ₂

H_A: _{1 2}

3)

H_O: _{1 2}

H_A: ₁> ₂

4)

H_O: _{1 2}

H_A: ₁= ₂

5)

H_O: ₁= ₂

H_A: _{1 2}

Question 14(1 point)

In a consumer research study, several Meijer and Walmart stores were surveyed at random and the average basket price was recorded for each. You wish to determine if the average basket price for Meijer is different from the average basket price for Walmart. It was found that the average basket price for 24 randomly chosen Meijer stores (group 1) was $62.528 with a standard deviation of $11.453. Similarly, a random sample of 18 Walmart stores (group 2) had an average basket price of $60.241 with a standard deviation of $11.4754. Perform a two independent samples t-test on the hypotheses Null Hypothesis: ₁= ₂, Alternative Hypothesis: _{1 2}. What is the test statistic and p-value of this test? You can assume that the standard deviations of the two populations are statistically similar.

Question 14 options:

1)

Test Statistic: 0.64, P-Value: 0.7371

2)

Test Statistic: 0.64, P-Value: 0.2629

3)

Test Statistic: 0.64, P-Value: 0.5258

4)

Test Statistic: -0.64, P-Value: 0.5258

5)

Test Statistic: 0.64, P-Value: 1.7371

Question 15(1 point)

It is believed that students who begin studying for final exams a week before the test score differently than students who wait until the night before. Suppose you want to test the hypothesis that students who study one week before score different from students who study the night before. A hypothesis test for two independent samples is run based on your data and a p-value is calculated to be 0.2082. What is the appropriate conclusion?

Question 15 options:

1)

We did not find enough evidence to say a significant difference exists between the average score of students who study one week before a test and the average score of students who wait to study until the night before a test.

2)

We did not find enough evidence to say the average score of students who study one week before a test is less than the average score of students who wait to study until the night before a test.

3)

We did not find enough evidence to say the average score of students who study one week before a test is greater than the average score of students who wait to study until the night before a test.

4)

The average score of students who study one week before a test is equal to the average score of students who wait to study until the night before a test.

5)

The average score of students who study one week before a test is significantly different from the average score of students who wait to study until the night before a test.

Question 16(1 point)

A medical researcher wants to examine the relationship of the blood pressure of patients before and after a procedure. She takes a sample of people and measures their blood pressure before undergoing the procedure. Afterwards, she takes the same sample of people and measures their blood pressure again. The researcher wants to test if the blood pressure measurements after the procedure are greater than the blood pressure measurements before the procedure. The hypotheses are as follows: Null Hypothesis: _D 0, Alternative Hypothesis: _D> 0. From her data, the researcher calculates a p-value of 0.0132. What is the appropriate conclusion? The difference was calculated as (after - before).

Question 16 options:

1)

We did not find enough evidence to say there was a significantly positive average difference in blood pressure.

2)

The average difference in blood pressure is less than or equal to 0.

3)

The average difference in blood pressure is significantly less than 0. The blood pressure of patients is higher before the procedure.

4)

The average difference in blood pressure is significantly larger than 0. The blood pressure of patients is higher after the procedure.

5)

The average difference in blood pressure is significantly different from 0. The blood pressures of patients differ significantly before and after the procedure.

Question 17(1 point)

Consumers Energy states that the average electric bill across the state is $60.85. You want to test the claim that the average bill amount is actually less than $60.85. The hypotheses for this situation are as follows: Null Hypothesis: 60.85, Alternative Hypothesis: < 60.85. If the true statewide average bill is $94.02 and the null hypothesis is not rejected, did a type I, type II, or no error occur?

Question 17 options:

1)

No error has occurred.

2)

We do not know the degrees of freedom, so we cannot determine if an error has occurred.

3)

Type II Error has occurred

4)

We do not know the p-value, so we cannot determine if an error has occurred.

5)

Type I Error has occurred.