Question

Question 11 pts

What is the critical value of z (that is, z*) for the 99% confidence level?

Group of answer choices

1.645

2.576

1.960

3.000

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Question 21 pts

The margin of error for your confidence interval will be:

Group of answer choices

.47

.36

.07

3.34

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Question 31 pts

Suppose the correct confidence interval is from 2 to 4 hours. Which of the following would be the correct interpretation of this interval?

Group of answer choices

There is a 99% probability the mean time MU students spend online per day is between 2 and 4 hours.

We are 95% sure the mean time MU students spend online per day is between 2 and 4 hours.

We are 95% sure the mean time the students surveyed spend online per day is between 2 and 4 hours.

99% of MU students spend between 2 and 4 hours online per day.

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Question 41 pts

Suppose you wish to decrease the margin of error to a quarter hour (that is .25 hours), still having 99% confidence in your conclusion. How many students must be surveyed?

Group of answer choices

180

212

98

13

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Question 51 pts

The margin of error (MOE) will decrease (resulting in a narrower interval and a more accurate estimate) in all the following situations EXCEPT which one?

Group of answer choices

A lower confidence level is used.

A larger sample size is used.

The variation in hours spent online is lower.

The sample is not a random sample.

Answer 1

Question 1

The critical value of z (that is, z*) for the 99% confidence level is  2.576

Question 2

The margin of error for your confidence interval = Z * Standard error

Multiply the z value with the standard error to get the answer.

Question 3

The correct interpretation of this interval is,

There is a 99% probability the mean time MU students spend online per day is between 2 and 4 hours.

Question 4

To decrease the margin of error to a quarter hour (that is .25 hours), the sample size is,

n = (z / E)^2 = (2.576 * / 0.25)^2

= 106.1724 *

Put the value of standard deviation in previpus part of the question to get the answer.

For example if the standard deviation is 1.3

n = 106.1724 * 1.3^2 = 180

Question 5

The margin of error (MOE) will decrease for lower confidence interval, large sample size, lower variation in hours spent. The answer is,

The sample is not a random sample.