STATS PRACTICE QUESTIONS

A two-tailed test is performed at a 5% level of significance. The p-value is determined to be .09. The null hypothesis _____.

should not be rejected

A two-tailed test at a .0694 level of significance has test statistic values of _____.

–1.82 and 1.82

The coefficient of variation is _____.

usually expressed as a percentage

In a residual plot against x that does NOT suggest we should challenge the assumptions of our regression model, we would expect to see a _____.

horizontal band of points centered near 0

Regression analysis was applied between sales (in $1000s) and advertising (in $100s), and the following regression function was obtained.

​= 80 + 6.2x

​Based on the above estimated regression line, if advertising is $10,000, then the point estimate for sales (in dollars) is _____.

$700,000

For a sample size of 30, changing from using the standard normal distribution to using the t distribution in a hypothesis test _____.

will result in the rejection region being smaller

An interval estimate is used to estimate _____.

population parameter

The level of significance is the _____.

maximum allowable probability of a Type I error

In hypothesis testing, the alternative hypothesis is _____.

the hypothesis concluded to be true if the null hypothesis is rejected

In hypothesis testing, if the null hypothesis has been rejected when the alternative hypothesis has been true, _____.

The correct decision has been made

A soft drink filling machine, when in perfect adjustment, fills the bottles with 12 ounces of soft drink. Any overfilling or underfilling results in the shutdown and readjustment of the machine. To determine whether or not the machine is properly adjusted, the correct set of hypotheses is _____.

H₀: μ = 12 H_a: μ ≠ 12

Which of the following does NOT need to be known in order to compute the p-value?

level of significance

Regression analysis was applied between sales (in $1000s) and advertising (in $100s), and the following regression function was obtained.

​= 500 + 4x

​Based on the above estimated regression line, if advertising is $10,000, then the point estimate for sales (in dollars) is _____.

$900,000

The proportion of the variation in the dependent variable y that is explained by the estimated regression equation is measured by the _____.

coefficient of determination

In a regression analysis, if SSE = 500 and SSR = 300, then the coefficient of determination is _____.

.375

Larger values of r² imply that the observations are more closely grouped about the _____.

least squares line

In regression and correlation analysis, if SSE and SST are known, then with this information the _____.

coefficient of determination can be computed

The numerical value of the coefficient of determination _____.

is positive if the correlation coefficient is negative

If the margin of error in an interval estimate of μ is 4.6, the interval estimate equals _____.

x ± 4.6

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

Using α = .04, a confidence interval for a population proportion is determined to be .65 to .75. If the level of significance is decreased, the interval for the population proportion _____.

becomes wider

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

becomes wider

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

standard normal distribution

The use of the normal probability distribution as an approximation of the sampling distribution of

is based on the condition that both np and n(1 – p) equal or exceed _____.

5

Excel's _____ function can be used to compute the sample covariance.

COVARIANCES

If r = 0.48 for data set A and r = –0.48 for data set B, which of the following is true?

The two data sets have the same level of correlation.

If a hypothesis is not rejected at a 5% level of significance, it _____.

will also not be rejected at the 1% level

The smaller the p-value,the _____.

greater the evidence against H₀

For a two-tailed hypothesis test about a population mean, the null hypothesis can be rejected if the confidence interval _____.

does not include µ₀

In hypothesis testing, the hypothesis tentatively assumed to be true is _____.

the null hypothesis

For a two-tailed hypothesis test about μ, we can use any of the following approaches EXCEPT compare the _____ to the _____.

level of significance; confidence coefficient

The level of significance in hypothesis testing is the probability of _____.

rejecting a true null hypothesis

The probability that the interval estimation procedure will generate an interval that contains the actual value of the population parameter being estimated is the _____.

confidence coefficient

As the degrees of freedom increase, the t distribution approaches the _____ distribution.

normal

If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient is _____.

.95

The mean of the t distribution is _____.

0

The t distribution should be used whenever _____.

the sample stabndard deviation is used to estimate the population standard deviation

The correlation coefficient ranges from which two values?

-1 and +1

The coefficient of variation is _____.

usually expressed as a percentage

For a two-tailed hypothesis test with a test statistic value of z = 2.05, the p-value is_____.

.0404

The average life expectancy of tires produced by Whitney Tire Company has been 40,000 miles. Management believes that due to a new production process, the life expectancy of its tires has increased. In order to test the validity of this belief, the correct set of hypotheses is _____.

H₀: μ ≤ 40,000 H_a: μ > 40,000

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 H_a: μ > 5

A two-tailed test is performed at a 5% level of significance. The p-value is determined to be .09. The null hypothesis _____.

should not be rejected

If a hypothesis is rejected at a 5% level of significance, it _____.

may be rejected or not rejected at the 1% level

A Type I error is committed when _____.

a true null hypothesis is rejected

The confidence associated with an interval estimate is called the _____.

confidence level

As the sample size increases, the margin of error _____.

decreases

Whenever the population standard deviation is unknown, which distribution is used in developing an interval estimate for a population mean?

t distribution

The probability that the interval estimation procedure will generate an interval that contains the actual value of the population parameter being estimated is the _____.

confidence coefficient

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

becomes wider

SSE can never be _____.

larger than SST

In regression analysis, the variable that is being predicted is the _____.

dependent variable

Application of the least squares method results in values of the y-intercept and the slope that minimizes the sum of the squared deviations between the _____.

observed values of the dependent variable and the predicted values of the dependent variable.

In regression and correlation analysis, if SSE and SST are known, then with this information the _____.

coefficient of determination can be computed

If the correlation coefficient is a negative value, then the coefficient of determination _____.

must be positive

The symbol for _____ is r_xy.

sample correlation

In a two-tailed hypothesis test, the null hypothesis should be rejected if the p-value is _____.

less than or equal to a

For a one-tailed test (upper tail) with a sample size of 900, the null hypothesis will be rejected at the .05 level of significance if the test statistic is _____.

greater than or equal to 1.645

When the p-value is used for hypothesis testing, the null hypothesis is rejected if _____.

p-value ≤ α

A two-tailed test is a hypothesis test in which the rejection region is _____.

in both tails of the sampling distribution

Excel's _____ function can be used to calculate a p-value for a hypothesis test.

NORM.S.DIST

It is possible for the coefficient of determination to be _____.

less than 1

The difference between the observed value of the dependent variable and the value predicted by using the estimated regression equation is called _____.

a residual

In determining an interval estimate of a population mean when σ is unknown, we use a t distribution with _____ degrees of freedom.

n-1

The confidence associated with an interval estimate is called the _____.

confidence level

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

standard normal distribution