# Liberty BUSI 230 Exam 4 Answers Complete Solutions

You would just need to put your values into excel. I put all mathematical formulas. They are the same questions with different values.

A positive value for a correlation indicates _____.

A researcher reports that there is no consistent relationship between grade point average and the number of hours spent studying for college students. The correlation between grade point average and the number of hours studying is an example of

A negative value for a correlation indicates ______.

Compute the Pearson correlation for the following data.

The value for a correlation can never be greater than 1.00.

Do heavier cars really use more gasoline? Suppose a car is chosen at random. Let x be the weight of the car (in hundreds of pounds), and let y be the miles per gallon (mpg).

## STATUS

Complete parts (a) through (e), given Σx = 303, Σy = 169, Σx2 = 12163, Σy2 = 3925, Σxy = 5945, and r ≈ -0.923.

(e) Find the value of the coefficient of determination r2. What percentage of the variation in y can be explained by the corresponding variation in x and the least-squares line? What percentage is unexplained? (Round your answer for r2 to three decimal places. Round your answers for the percentages to one decimal place.)

(f) Suppose a car weighs x = 32 (hundred pounds). What does the least-squares line forecast for y = miles per gallon? (Round your answer to two decimal places.)

Let x be the average number of employees in a group health insurance plan, and let y be the average administrative cost as a percentage of claims.

As x increases, does the value of r imply that y should tend to increase or decrease? Explain your answer.

For which of the following correlations would the data points be clustered most closely around a straight line?

Let x = age in years of a rural Quebec woman at the time of her first marriage. In the year 1941, the population variance of x was approximately σ2 = 5.1. Suppose a recent study of age at first marriage for a random sample of 41 women in rural Quebec gave a sample variance s2 = 3.0. Use a 5% level of significance to test the claim that the current variance is less than 5.1. Find a 90% confidence interval for the population variance.

The following table shows ceremonial ranking and type of pottery sherd for a random sample of 434 sherds at an archaeological location.

Use a chi-square test to determine if ceremonial ranking and pottery type are independent at the 0.05 level of significance.

Use a 5% level of significance to test the claim that the age distribution of the general Canadian population fits the age distribution of the residents of Red Lake Village.

The age distribution of the Canadian population and the age distribution of a random sample of 455 residents in the Indian community of a village are shown below.

Two plots at Rothamsted Experimental Station were studied for production of wheat straw. For a random sample of years, the annual wheat straw production (in pounds) from one plot was as follows.

Use a calculator to verify that, for this plot, the sample variance is s2 ≈ 0.304.

Another random sample of years for a second plot gave the following annual wheat production (in pounds).

Use a calculator to verify that the sample variance for this plot is s2 ≈ 0.420.

Test the claim that there is a difference (either way) in the population variance of wheat straw production for these two plots. Use a 5% level of signifcance.