Question 1

Random samples of 200 men and 200 women were collected and their resting pulse rates were measured, to estimate how much mean resting pulse rates differ for men and women in the population. An analyst mistakenly paired the observations and constructed an approximate 95% confidence interval for the mean difference to be (5$\pm$2×0.2) beats per minute. If the data had been analyzed correctly, finding an approximate 95% confidence interval for the difference in population means, which of the following parts of the interval would be different?

Accepted Answer

A)  The sample statistic of 5 beats per minute. 
B)  The multiplier of 2. 
C)  The standard error of 0.2. 
D)  None of the parts would be different; it is an equivalent analysis.

Question 2

Use the following information for questions:
 A union representative has collected some data on the hourly pay of workers in the area. He is curious to find out if hourly pay actually increases with age. He does not have the actual ages of the workers in his sample, but he does have age group information. For now, he wishes to compare the young workers (18-30 years old) with the middle aged workers (31-45 years old) by calculating a confidence interval for the difference in population mean salaries.
-The 90% confidence interval for the difference in average hourly pay (young - middle aged) was found to be
(-2.55, 1.43). Based on this interval, what conclusion can we draw about the average hourly pay for these two age groups?

Accepted Answer

The answer of Use the following information for questions:
 A...

Question 3

The heights of a sample of n = 18 female college students will be used to create a 98% confidence interval for the mean height of all female college students. What is the correct t* multiplier for this interval?

Accepted Answer

A)  2.11 
B)  2.55 
C)  2.57 
D)  2.90

Question 4

The WISC scores (similar to IQ test scores) of a sample of n = 20 5th graders will be used to create a 99% confidence interval for the mean WISC score of all 5th graders. What is the correct t* multiplier for this interval?

Accepted Answer

A)  2.86 
B)  3.55 
C)  2.54 
D)  2.85

Question 5

Random samples of 5 Japanese women and 10 Japanese men showed an average life span of 83 years for the women and 77 years for the men. The standard deviation was 2 years for the women and 1 year for the men. Calculate a 95% confidence interval for the difference in average life spans (women $\mu$ men). Assume that the life spans are normally distributed, but do not assume the population variances are equal, and use the conservative "by-hand" estimate for the degrees of freedom.

Accepted Answer

The answer of Random samples of 5 Japanese women and...

Question 6

Use the following information for questions:
 For a random sample of n = 203 adults in a survey, here is a summary of responses to "How long did you sleep last night?" 
-Which of the following provides an approximate 95% confidence interval for the mean hours of sleep the previous night in the population represented by the sample?

Accepted Answer

A)  6.42$\pm$2×0.11 
B)  6.42$\pm$2×$\frac{0.11}{\sqrt{203}}$ 
C)  6.42 $\pm$ 0.11 
D)  6.42$\pm$2×1.56

Question 7

Use the following information for questions:
 Managerial training programs often teach supervisory skills. Are these training programs effective? A company psychologist administers a test to each of 10 supervisors before and after attending such a training program. Higher scores indicate increased supervisory skills. The results are used to estimate the mean improvement in supervisory skills.
-Explain why this is a paired data design.

Accepted Answer

The answer of Use the following information for questions:
 Managerial...

Question 8

A randomly selected sample of n = 51 men in Brazil had an average lifespan of 59 years. The standard deviation was 10 years, and the standard error of the mean is 1.400. Calculate a 90% confidence interval for the average lifespan for all men in Brazil.

Accepted Answer

A)  (42.2, 75.8) 
B)  (56.6, 61.4) 
C)  (56.2, 61.8) 
D)  None of the above

Question 9

Which of the following helps determine the standard error for a confidence interval for a mean?

Accepted Answer

A)  The sample size(s). 
B)  The sample estimate. 
C)  The true value of the population parameter. 
D)  The confidence level.

Question 10

For which one of the following situations was a procedure for finding a confidence interval not covered in the textbook?

Accepted Answer

A)  A mean difference for paired data. 
B)  A difference in means for two independent samples. 
C)  A difference in proportions for paired data. 
D)  A difference in proportions for two independent samples.

Question 11

Use the following information for questions:
 For a random sample of n = 203 adults in a survey, here is a summary of responses to "How long did you sleep last night?" 
-What confidence level would be associated with the interval 6.42 - 0.11 as a confidence interval for the population mean $\mu$?

Accepted Answer

A)  50% 
B)  68% 
C)  90% 
D)  95%

Question 12

A random sample of 60 mathematics majors spent an average of $200.00 for textbooks for a term, with a standard deviation of $22.50. A random sample of 40 English majors spent an average of $180.00 for textbooks that term, with a standard deviation of $18.30. Calculate a 90% pooled confidence interval for the difference in average amounts spent on textbooks (math majors - English majors).

Accepted Answer

A)  (12.91, 27.09) 
B)  (11.50, 28.50) 
C)  (13.19, 26.81) 
D)  None of the above

Question 13

The cholesterol levels of a random sample of 100 men are measured. The sample mean is 188 and the sample standard deviation is 40. Which of the following provides a 95% confidence interval for the population mean?

Accepted Answer

A)  188$\pm$(1.98)(0.4) 
B)  188 $\pm$(1.98)(4) 
C)  188 $\pm$ (1.98)(40) 
D)  188 $\pm$(1.98)(4000)

Question 14

Which of the following studies describes a paired data design?

Accepted Answer

A)  The testosterone levels of male doctors and male college professors are compared 
B)  40 students measure their blood pressure twice--first while resting and then again after running in place for 10 minutes. 
C)  The mean blood pressure of men is compared to the mean blood pressure of women 
D)  All of choices A, B, and C involve paired data.

Question 15

Use the following information for questions:
 Refer to the following statistical summary of the left foot lengths (in centimeters) for a random sample of 76 college men. 
-Give an approximate 95% confidence interval for the average left foot length for college men.

Accepted Answer

The answer of Use the following information for questions:
 Refer...

Question 16

Conscientiousness is a tendency to show self-discipline, act dutifully, and aim for achievement. The trait shows a preference for planned rather than spontaneous behavior. A random sample of 650 students is asked to fill out the Hogan Personality Inventory (HPI) to measure their level of conscientiousness. The 300 undergraduate students scored an average of 145 with a standard deviation of 16. The 350 graduate students had a mean score of 153 with a standard deviation of 21. What is the standard error for the difference between the two sample means?

Accepted Answer

A)  18.5 
B)  2.11 
C)  1.45 
D)  2.05

Question 17

Use the following information for questions:
 For a randomly selected sample of 20 new mothers in the year 2000, the mean age was 24.6 years. For a randomly selected sample of 10 new mothers in 1970, the mean age was 21.4 years. The difference between the mean ages is 3.2 years, and the standard error of the difference is 1.366. Assume that the ages of new mothers are normally distributed, do not assume the population variances are equal, and use the conservative "by hand" estimate for the degrees of freedom.
-Calculate a 99% confidence interval for the difference in population mean ages of new mothers in the two years (year 2000 - year 1970).

Accepted Answer

A)  (-1.24, 7.64) 
B)  (-1.13, 7.53) 
C)  (0.47, 5.93) 
D)  None of the above

Question 18

A researcher asked random samples of 50 kindergarten teachers and 50 12S1U1P1thS1S1P0 grade teachers how much money they spent out-of-pocket on school supplies in the previous school year, to see if teachers at one grade level spend more than the other. A 95% confidence interval for$\mu$S1U1B1KS1U1B0-$\mu$S1U1B11S1U1B0S1U1B12S1U1B0 is $30 to $50. Based on this result, it is reasonable to conclude that

Accepted Answer

A)  95% of all kindergarten and 12S1U1P1thS1S1P0 grade teachers spend between $30 and $50 on average. 
B)  95% of all kindergarten teachers spend between $30 and $50 more then 95% of all 12th grade teachers. 
C)  kindergarten teachers spend more on average than do 12S1U1P1thS1S1P0 grade teachers. 
D)  12S1U1P1thS1S1P0 grade teachers spend more on average than do kindergarten teachers.

Question 19

Use the following information for questions:
 Refer to the following statistical summary of the left foot lengths (in centimeters) for a random sample of 76 college men. 
-In terms of the notation of this course, what is the correct way to express the "Mean" shown in the output?

Accepted Answer

The answer of Use the following information for questions:
 Refer...

Question 20

A randomly selected sample of 100 students had an average grade point average (GPA) of 3.2 with a standard deviation of 0.2. The standard error of the sample mean is

Accepted Answer

A)  0.020 
B)  0.200 
C)  1.600 
D)  2.000

Exam 11: Estimating Means With Confidence

The heights of a sample of n = 18 female college students will be used to create a 98% confidence interval for the mean height of all female college students. What is the correct t* multiplier for this interval?

The WISC scores (similar to IQ test scores) of a sample of n = 20 5^th graders will be used to create a 99% confidence interval for the mean WISC score of all 5^th graders. What is the correct t* multiplier for this interval?

A randomly selected sample of n = 51 men in Brazil had an average lifespan of 59 years. The standard deviation was 10 years, and the standard error of the mean is 1.400. Calculate a 90% confidence interval for the average lifespan for all men in Brazil.

Which of the following helps determine the standard error for a confidence interval for a mean?

For which one of the following situations was a procedure for finding a confidence interval not covered in the textbook?

The cholesterol levels of a random sample of 100 men are measured. The sample mean is 188 and the sample standard deviation is 40. Which of the following provides a 95% confidence interval for the population mean?

Which of the following studies describes a paired data design?

Use the following information for questions: Refer to the following statistical summary of the left foot lengths (in centimeters) for a random sample of 76 college men. -Give an approximate 95% confidence interval for the average left foot length for college men.

Use the following information for questions: Refer to the following statistical summary of the left foot lengths (in centimeters) for a random sample of 76 college men. -In terms of the notation of this course, what is the correct way to express the "Mean" shown in the output?

A randomly selected sample of 100 students had an average grade point average (GPA) of 3.2 with a standard deviation of 0.2. The standard error of the sample mean is

Exam 11: Estimating Means With Confidence

The heights of a sample of n = 18 female college students will be used to create a 98% confidence interval for the mean height of all female college students. What is the correct t* multiplier for this interval?

The WISC scores (similar to IQ test scores) of a sample of n = 20 5th graders will be used to create a 99% confidence interval for the mean WISC score of all 5th graders. What is the correct t* multiplier for this interval?

A randomly selected sample of n = 51 men in Brazil had an average lifespan of 59 years. The standard deviation was 10 years, and the standard error of the mean is 1.400. Calculate a 90% confidence interval for the average lifespan for all men in Brazil.

Which of the following helps determine the standard error for a confidence interval for a mean?

For which one of the following situations was a procedure for finding a confidence interval not covered in the textbook?

Use the following information for questions: For a random sample of n = 203 adults in a survey, here is a summary of responses to "How long did you sleep last night?" -What confidence level would be associated with the interval 6.42 - 0.11 as a confidence interval for the population mean μ\muμ ?

The cholesterol levels of a random sample of 100 men are measured. The sample mean is 188 and the sample standard deviation is 40. Which of the following provides a 95% confidence interval for the population mean?

Which of the following studies describes a paired data design?

Use the following information for questions: Refer to the following statistical summary of the left foot lengths (in centimeters) for a random sample of 76 college men. -Give an approximate 95% confidence interval for the average left foot length for college men.

Use the following information for questions: Refer to the following statistical summary of the left foot lengths (in centimeters) for a random sample of 76 college men. -In terms of the notation of this course, what is the correct way to express the "Mean" shown in the output?

A randomly selected sample of 100 students had an average grade point average (GPA) of 3.2 with a standard deviation of 0.2. The standard error of the sample mean is

The WISC scores (similar to IQ test scores) of a sample of n = 20 5^th graders will be used to create a 99% confidence interval for the mean WISC score of all 5^th graders. What is the correct t* multiplier for this interval?