Question 1

If you are constructing a confidence interval for a single mean, the confidence interval will___________ with an increase in the sample size.

A.decrease

B.increase

C.increase or decrease, depending on the sample data

D.stay the same

Reset Selection

Question 2

In order to be accepted into a top university, applicants must score within the top 5% on the SAT exam. Given that SAT test scores are normally distributed with a mean of 1000 and a standard deviation of 200, what is the lowest possible score a student needs to qualify for acceptance into the university?

A.1330

B.1400

C.1250

D.1100

Question 3

In constructing a confidence interval estimate for a population mean, when we replace with the sample standard deviation (s), we introduce a new source of variability and the sampling distribution we use is:

A.the normal distribution

B.F- distribution

C.chi-square distribution

D.t -distribution

Question 4

Which of the following will make a confidence interval narrower and more precise?

A.Smaller sample size and higher confidence level

B.Larger sample size and lower confidence level

C.Larger sample size and higher confidence level

D.Smaller sample size and lower confidence level

Question 5

Confidence intervals are a function of which of the following three things?

A.The population, the sample, and the standard deviation

B.The data in the sample, the confidence level, and the sample size

C.The sample, the variable of interest, and the degrees of freedom

D.The sampling distribution, the confidence level, and the degrees of freedom

Question 6

In a study of elephants a researcher wishes to determine the average weight of a certain subspecies of elephants. From previous studies, the standard deviation of the weights of elephants in this subspecies is known to be 1500 pounds. How many elephants does the researcher need to weigh so that he can be 80% confident that the average weight of elephants in his sample is within 350 pounds of the true average weight for this subspecies?

A.31

B.166

C.50

D.39

Question 7

The upper limit of the 90% confidence interval for the population proportion p, given that n = 100; and p^= 0.20 is

A.0.2658

B.0.7342

C.0.4684

D.0.5316

Question 8

A sample of 23 European countries found that the variance of life expectancy was 7.3 years. What is the 95% confidence interval estimate for the variance of life expectancy in Europe?

A.27.2 < < 118.3

B.5.6 < < 10.3

C.4.4 < < 14.6

D.28.9 < < 115.0

Question 9

A previous study of nickels showed that the standard deviation of the weight of nickels is 150 milligrams. How many nickels does a coin counter manufacturer need to weigh so that she can be 98% confident that her sample mean is within 25 milligrams of the true average weight of a nickel?

A.36

B.196

C.239

D.139

Question 10

The lower limit of the 95% confidence interval for the population proportion p, given that n = 300; and = 0.10 is 0.1339.

True

False

Question 11

2.0 The upper limit of the 90% confidence interval for the population proportion p, given that n = 100; and p^= 0.20 is 0.2341.

True

False