Question

1. We wish to develop a confidence interval for the population mean. The population standard deviation is known. We have a sample of 40 observations. We decide to use the 92 percent level of confidence. The appropriate value of z is:

a)1.96

b)1.65

c)2.58

d)1.75

2.    A random sample of 90 days at a coffee shop produces a mean daily sales of $1200. The standard deviation of the population of daily sales is $210. What is the 99% confidence interval for the mean of the population of daily sales?

a)$1200 ± $6

b)$1200 ± $43

c)$1200 ± $57

d)$1200 ± $5

3.    The mean daily sales for a book store were $700 over the last 20 days with a sample standard deviation of $75. What is the 95% confidence interval?

a)$700 ± $43

b)$700 ± $35

c)$700 ± $12

d)$700 ± $33

4.    An economist wants to estimate the proportion of Canadians who own their homes. A random sample of 800 people reveals 544 own their homes. Develop a 95% confidence interval for the population proportion.

a)0.68 ± 0.053

b)0.68 ± 0.032

c)0.32 ± 0.032

d)0.68 ± 0.027

5.    A pilot study shows that 64% of people living in the downtown core are single. A market research company wants to verify this claim. The company requires a 95% confidence interval. How many residents should be interviewed to keep the margin of error within 0.02 of the population proportion?

a)23

b)9604

c)2213

d)6147

6.    The mean daily sales for a bookstore were $700 over the last 60 days. The standard deviation of this population is $85. What is the 95% confidence interval?

a)$700 ± $2.78

b)$700 ± $21.51

c)$700 ± $28.31

d)$700 ± $3.66

7.    A random sample of 300 drivers revealed that 96 of them had received a speeding ticket in the last 3 months. Construct a 95% confidence interval for the number of drivers who receive speeding tickets over a three-month period.

a)0.32 ± 0.027

b)0.32 ± 0.001

c)0.32 ± 0.069

d)0.32 ± 0.053

8.    A survey is being planned to determine the mean amount of time children under 6 spend watching TV. A pilot survey indicated the mean time was 22 hours per week with a standard deviation of 3 hours. The mean viewing time is to be estimated within 0.5 hours. How many children must be studied to obtain a 95% confidence interval?

a)139

b)12

c)7438

d)87

Answer 1