Question 4(1 point)

Suppose that the middle 68% of monthly food expenditures for a family of four fall between 737.06 and 895.1. Give an approximate estimate of the standard deviation of the expenditures. Assume the expenditures have a normal distribution.

Question 4 options:

1)

158.04

2)

-79.02

3)

39.51

4)

816.08

5)

79.02

Question 5(1 point)

Suppose that the distribution of income in a certain tax bracket is approximately normal with a mean of $49,561.24 and a standard deviation of $2,394.256. Approximately 22.58% of households had an income greater than what dollar amount?

Question 5 options:

1)

4,265,553

2)

47,758.97

3)

We do not have enough information to calculate the value.

4)

4,364,675

5)

51,363.52

Question 6(1 point)

According to estimates by the office of the Treasury Inspector General of IRS, approximately 0.0484 of the tax returns filed are fraudulent or will contain errors that are purposely made to cheat the IRS. In a random sample of 227 independent returns from this year, what is the probability that exactly 7 will be fraudulent or will contain errors that are purposely made to cheat the IRS?

Question 6 options:

1)

0.8623

2)

0.0635

3)

0.0318

4)

0.1377

5)

0.9365

Question 7(1 point)

A consumer wanted to find out how accurate Siri (an Apple digital assistant) is, so he asked questions on general facts and recorded how many Siri got right. Out of the 247 questions he asked Siri, Siri responded correctly to 230 of them. What is the estimate of the population proportion? What is the standard error of this estimate?

Question 7 options:

1)

Estimate of proportion: 0.931, Standard error: 0.0010.

2)

The true population proportion is needed to calculate this.

3)

Estimate of proportion: 0.069, Standard error: 0.0161.

4)

Estimate of proportion: 0.069, Standard error: 0.0010.

5)

Estimate of proportion: 0.931, Standard error: 0.0161.

Question 8(1 point)

A scientist is interested in the response of red blood cell counts in adult males after extended use of a particular medication. The average expected blood count is 4.99 million cells/mcL with a standard deviation of 0.209 million cells/mcL. You randomly select 179 men to participate in a study. What is the probability that the average red blood count after continued use of the medication is greater than 4.98 million cells/mcL?

Question 8 options:

1)

0.4809

2)

-19.8068

3)

0.7390

4)

0.2610

5)

0.5191

Question 9(1 point)

The owner of a local golf course wants to determine the average age of the golfers that play on the course in relation to the average age in the area. According to the most recent census, the town has an average age of 25.43. In a random sample of 27 golfers that visited his course, the sample mean was 42.59 and the standard deviation was 8.966. Using this information, the owner calculated the confidence interval of (39.65, 45.53) with a confidence level of 90%. Which of the following statements is the best conclusion?

Question 9 options:

1)

We are 90% confident that the average age of all golfers that play on the golf course is greater than 25.43

2)

The percentage of golfers with an age greater than 25.43 is 90%.

3)

We are 90% confident that the average age of all golfers that play on the golf course is less than 25.43

4)

The average age of all golfers does not significantly differ from 25.43.

5)

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

Question 10(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 20 golfers play a round of 18 holes on his golf course and records their scores. Later that week, he has the same 20 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 -2.74 strokes and the standard deviation of the differences is 6.841 strokes. The owner uses this information to calculate the 95% confidence paired t-interval of (-5.942, 0.462). Which statement is the correct interpretation of this interval?

Question 10 options:

1)

We are 95% confident that the average difference in scores between the two courses for all golfers is between -5.942 and 0.462.

2)

The proportion of all golfers that had a difference in scores between the two courses is 95%.

3)

We are 95% confident that the average difference in the scores of the golfers sampled is between -5.942 and 0.462.

4)

We are certain the average difference in scores between the two courses for all golfers is between -5.942 and 0.462.

5)

We are 95% confident that the difference between the average score on the owner's golf course and the average score on the friend's golf course is between -5.942 and 0.462.