All you need to do is explain how to solve each using the TI-84 Plus (You can download a free 90 day version online for your PC).

Correct Answers:

63) B, 64) A, 65) D, 66) A, 67) C, 68) C, 69) D, 70) A, 71) A, 72) A, 73) D

63)Scientists want to estimate the mean weight gain of mice after they have been fed a special diet. From previous studies, it is known that the weight gain is normally distributed with standard deviation 2.5 grams. How many mice must be weighed so that a 99% confidence interval for mean weight will have a margin of error of 0.9 grams?

A) 2 B) 52 C) 8 D) 18

64)A sample of size n = 17 is drawn from a normal population. Find the critical value t ^a/2 needed to construct a 99% confidence interval.

A) 2.921 B) 2.584 C) 2.576 D) 2.898

65) A sample of size n = 22 is drawn from a normal population. Find the critical value t^ a/2 needed to construct a 98% confidence interval.

A) 2.326 B) 2.508 C) 2.189 D) 2.518

66) A sample of size n = 11 has a sample mean x = 14.5 and sample standard deviation s = 2.1. It is reasonable to assume that the population is approximately normal. Construct a 99% confidence interval for the population mean u. A) (12.5, 16.5) B) (13.9, 15.1) C) (12.8, 16.2) D) (13.1, 15.9) 67) A sample of 132 tobacco smokers who recently completed a new smoking-cessation program were asked to rate the effectiveness of the program on a scale of 1 to 10, with 10 corresponding to "completely effective" and 1 corresponding to "completely ineffective". The average rating was 5.7 and the standard deviation was 4.7. Construct a 95% confidence interval for the mean score.

A) (5.4, 6.0) B) (0, 5.7) C) (4.9, 6.5) D) (5.3, 6.1) 68) A survey asked 10 adults how many years of education they had. The sample mean was 13.55 with a standard deviation of 2.94. It is reasonable to assume that the population is approximately normal. Construct a 90% confidence interval for the mean number of years of education.

A) (-3.5, 30.6) B) (-23.1, 23.1) C) (11.8, 15.3) D) (13.0, 14.1) 69) A machine used to fill beverage cans is supposed to put exactly 12 ounces of beverage in each can, but the actual amount varies randomly from can to can. In a sample of 50 cans, the standard deviation of the amount was s = 0.05 ounces. A simple random sample of filled cans will have their volumes measured, and a 95% confidence interval for the mean fill volume will be constructed. Estimate the number of cans that must be sampled for the margin of error to be equal to 0.01 ounces.

A) 96 B) 100 C) 101 D) 97

70) In a recent poll, 92 of the 207 respondents said that they were in favor of a new gas tax. Find the point estimate needed to construct a confidence interval for the proportion of citizens in favor of this gas tax.

A) 0.4444 B) 0.5556 C) 92 D) 0.03454

71) In a sample of technical college students taken last semester, 124 of the 228 students stated they planned on transferring to a four-year institution. Find the margin of error for a 98% confidence interval for the proportion of students who plan to transfer to a four-year instutution.

A) 0.07673 B) 0.4561 C) 0.03299 D) 0.5439

72) In a recent fashion poll, 89 out of 178 respondents said that bell-bottom pants are back in style. Construct a 90% confidence interval for proportion of people who think bell-bottom pants are back "in."

A) (0.438, 0.562) B) (0.463, 0.537) C) (0.452, 0.548) D) (0.399, 0.601) 73) An Internet service provider sampled 580 customers and found that 95 of them experienced an interruption in their service during the previous month. Construct a 90% confidence interval for the proportion of all customers who have experienced a service interruption.

A) (0.811, 0.861) B) (0.144, 0.183) C) (0.164, 0.836) D) (0.139, 0.189)