1. A researcher reports survey results by stating that the standard error of the mean is $22. The population standard deviation is = $132.

How large was the sample used in this survey?

a) 64

b) 55

c) 48

d) 36

In the previous question, what is the probability that x is within $30 from the population mean?

a) 0.8986

b) 0.9426

c) 0.8262

d) 0.9108

The 95% margin of error for the sampling distribution in the previous question is:

a) 43.12

b) 45.66

c) 25.83

d) 30.87

2. The mean annual cost of full-coverage auto insurance is = $1,850. Assume the population standard deviation is = $405.

The standard error of the sampling distribution of the mean of random samples of size n = 81 automobile insurance policies is,

a) $45.00

b) $48.45

c) $50.65

d) $52.00

In the previous question, the fraction of sample means the fall within the interval ($1,800, $1,900) is,

a) 0.8414

b) 0.8098

c) 0.7738

d) 0.7330

The margin of error for the middle interval which captures 95% of the means from samples of size n = 81 is,

a) 91.4

b) 88.2

c) 73.8

d) 65.3

In the previous question, the middle interval that captures 95% of all sample means from samples of size n = 81 is,

a) $1,784.8 $1,915.3

b) $1,776.2 $1,923.8

c) $1,761.8 $1,938.2

d) $1,758.7 $1,941.4

To achieve a 95% margin or error of $25 for the sampling distribution, the minimum sample size is,

a) 1009

b) 948

c) 864

d) 787

3. The mean birth weight of babies is = 3400 grams with a standard deviation of = 590 grams.

For samples of size n = 30 babies selected from this population, the standard error of the sample mean is:

a) 107.72

b) 104.72

c) 77.46

d) 83.44

For samples of size n = 30 babies selected from this population, the fraction of sample means that fall within 3300 and 3500 grams is,

a) 0.7698

b) 0.8064

c) 0.6476

d) 0.6830

The margin of error for the middle interval which captures 0.95 fraction (95 percent) of all means from samples of size n = 50 is:

a) 189.4

b) 163.5

c) 211.1

d) 121.0

4. The amount of time a bank teller spends with each customer is normally distributed with a mean of = 4.2 minutes and standard deviation of = 1.2 minutes.

A random sample of n = 9 customers is selected. The probability that the mean time spent with the customers in the sample is greater than 4.9 minutes is,

a) 0.0401

b) 0.0516

c) 0.0606

d) 0.0735

In random samples of size n = 9, 95% of the sample means fall within ______ and ______ minutes.

a) 3.6 4.8

b) 3.5 4.9

c) 3.4 5.0

d) 3.3 5.1

5. In a referendum the proportion of voters who favor the proposition is = 0.52. A pollster polls a random sample of n = 425 voters.

The probability that the poll will wrongly predict the defeat of the propositions is:

a) 0.1151

b) 0.1515

c) 0.2033

d) 0.2451

In the previous question the margin of error for the interval that would capture 95% of proportions (p's) from samples of n = 425 voters is,

a) 0.047

b) 0.040

c) 0.035

d) 0.032

In the previous question to obtain a margin of error of 0.03 for a middle interval which would capture 95% of sample proportions, what should the minimum sample size be?

a) 995

b) 1005

c) 1066

d) 1088

Consider the middle interval in the sampling distribution of p: (p = 0.735, p = 0.785). Given an error probability of 5 percent, what is the sample size in this sampling distribution?

a) 1064

b) 1098

c) 1122

d) 1158

The proportion of visitors to the Grand Canyon National Park who are foreigners is = 0.60. In the sampling distribution of the proportion for samples of size n = 310 visitors,

the margin of error for the interval that contains the middle 90% of sample proportions is,

a) 0.036

b) 0.030

c) 0.038

d) 0.046

In the previous question, the margin of error which would capture 98% of sample proportions is,

a) 0.065

b) 0.040

c) 0.039

d) 0.043