# Connexions

You are here: Home » Content » Elementary Statistics: Quiz 8: Confidence Intervals

## Navigation

### Recently Viewed

This feature requires Javascript to be enabled.

# Elementary Statistics: Quiz 8: Confidence Intervals

Summary: This module is a quiz containing 10 multiple choice questions covering topics related to confidence intervals. This module is part of a set of companion resources to Collaborative Statistics (col10522) by Barbara Illowsky and Susan Dean.

## Exercise 1

When constructing a confidence interval for the population mean, the case where the population standard deviation is known is __________.

• A. possible, and the most common
• B. possible, but not common
• C. possible, and quite common
• D. impossible

## Exercise 2

When constructing a Confidence Interval, which case is preferable?

• A. large confidence level, small confidence interval
• B. small confidence level, small confidence interval
• C. small confidence level, large confidence interval
• D. large confidence level, large confidence interval

## Exercise 3

Which of the following is NOT a point estimate?

• A. x-bar
• B. p-hat or p-prime
• C. s
• D. sigma

## Exercise 4

When should the Student-t distribution be used in constructing a confidence interval for the population mean?

• A. When the population proportion is known and the underlying population is normally distributed.
• B. When the population standard deviation is unknown and the underlying population is normally distributed.
• C. When the population proportion is unknown and the underlying population is normally distributed.
• D. When the population standard deviation is known and the underlying population is normally distributed.

## Exercise 5

When constructing a Confidence Interval for the population mean and both the sample standard deviation and the population standard deviation are known, which of the following should be used?

• A. normal distribution using the sample standard deviation
• B. normal distribution using the population standard deviation
• C. student-t distribution using the population standard deviation
• D. student-t distributuion using the sample standard deviation

## Exercise 6

A study was done to determine the proportion of voters that feel that their local government is doing an adequate job. Of the 160 voters surveyed, 144 feel that their local government is doing an adequate job. Calculate the 95% confidence interval for the true proportion of voters that feel that their government is doing an adequate job.

• A. (0.85, 0.95)
• B. 0.90
• C. (0.80, 1.00)
• D. (144, 160)

## Exercise 7

To reduce the error bound in a future study, which of the following should be done?

• A. increase the sample size n
• B. decrease the sample size n
• C. conduct a biased survey
• D. increase the confidence level

## Exercise 8

A study was done to determine the average number of homes that a homeowner owns in his or her lifetime. For the 60 homeowners surveyed, the sample average was 4.2 and the sample standard deviation was 2.1. Calculate the 95% confidence interval for the true average number of homes that a person owns in his or her lifetime.

• A. (3.90, 4.50)
• B. (3.66, 4.74)
• C. (4.01, 4.39)
• D. (3.67, 4.73)

## Exercise 9

A study was done to determine the average number of homes that a homeowner owns in his or her lifetime. For the 60 homeowners surveyed, the sample average was 4.2 and the sample standard deviation was 2.1. The distribution to use to calculate the 95% confidence interval is ________________.

• A. Exponential
• B. Student-t with df = 59
• C. Student-t with df = 60
• D. Binomial

## Exercise 10

Calculate the error bound for a survey in which the sample mean is 5, the population standard deviation is 3, the confidence level is 0.90, and the number surveyed is 12.

• A. 1.56
• B. 1.42
• C. (3.58, 6.42)
• D. (3.44, 6.56)

## Content actions

PDF | EPUB (?)

### What is an EPUB file?

EPUB is an electronic book format that can be read on a variety of mobile devices.

### Downloading to a reading device

For detailed instructions on how to download this content's EPUB to your specific device, click the "(?)" link.

| More downloads ...

### Add module to:

My Favorites (?)

'My Favorites' is a special kind of lens which you can use to bookmark modules and collections. 'My Favorites' can only be seen by you, and collections saved in 'My Favorites' can remember the last module you were on. You need an account to use 'My Favorites'.

| A lens I own (?)

#### Definition of a lens

##### Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

##### What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

##### Who can create a lens?

Any individual member, a community, or a respected organization.

##### What are tags?

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

| External bookmarks