Exam 3 Practice

Whenever using the t distribution in interval estimation, we must assume that _____.

• the population is approximately normal

• the sample size is less than 30

• the finite population correction factor is necessary

• a random sample was selected

In hypothesis testing if the null hypothesis is rejected, _____.

• no conclusion can be drawn from the test

• the evidence supports the alternative hypothesis

• the data must have been collected incorrectly

• the alternative hypothesis must also be rejected

The use of the normal probability distribution as an approximation of the sampling distribution of p-bar is based on the condition that both np and n(1 − p) equal or exceed _____.

• .05

• 30

• 15

• 5

For a two-tailed test with a sample size of 40, the null hypothesis will NOT be rejected at a 5% level of significance if the test statistic is _____.

• greater than 1.96

• greater than −1.645

• less than 1.645

• between −1.96 and 1.96, exclusively

If the cost of a Type I error is high, a smaller value should be chosen for the _____.

• confidence coefficient

• critical value

• test statistic

• level of significance

To compute the minimum sample size for an interval estimate of μ when the population standard deviation is known, we must first determine all of the following EXCEPT _____.

• population standard deviation

• degrees of freedom

• desired margin of error

• confidence level

For the interval estimation of μ when σ is assumed known, the proper distribution to use is the _____.

• t distribution with n - 1 degrees of freedom

• t distribution with n - 2 degrees of freedom

• standard normal distribution

• t distribution with n degrees of freedom

A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to .90, the interval for μ _____.

• becomes narrower

• does not change

• becomes wider

• becomes 1

When the level of confidence increases, the confidence interval _____.

• becomes narrower

• becomes negative

• becomes wider

• stays the same

The manager of an automobile dealership is considering a new bonus plan in order to increase sales. Currently, the mean sales rate per salesperson is five automobiles per month. The correct set of hypotheses for testing the effect of the bonus plan is ____.

• H0: μ = 5; Ha: μ > 5

• H0: μ < 5; Ha: μ = 5

• H0: μ = 5; Ha: μ < 5

• H0: μ > 5; Ha: μ = 5