Chapter 10 – Comparisons Involving Means, Experimental Design, and Analysis of Variance
We want to determine whether or not there is a significant difference between the average
salaries of the employees at the two companies. Compute the test statistic.
Compute the p-value; and at 95% confidence, test the hypotheses.
151. In order to estimate the difference between the yearly incomes of marketing managers in the East and West of the
United States, the following information was gathered.
Develop an interval estimate for the difference between the average yearly incomes of the
marketing managers in the East and West. Use α = 0.05.
At 95% confidence, use the p-value approach and test to determine if the average yearly
income of marketing managers in the East is significantly different from the West.
Test statistic t = -3.937 (df = 80), p-value < .005, reject Ho and conclude that there is a
152. In order to estimate the difference between the average daily sales of two branches of a department store, the
following data has been gathered.
Sample standard deviation (in $1,000)
Determine the point estimate of the difference between the means.
Determine the degrees of freedom for this interval estimation.
Compute the margin of error.
Develop a 95% confidence interval for the difference between the two population means.
46 (rounded down from 46.56)
3 ± 2.591 (In dollars it will be from $409 to $5,591)
153. A potential investor conducted a 144 day survey in each theater in order to determine the difference between the
average daily attendance at the North Mall and South Mall theaters. The North Mall Theater averaged 630 patrons per
day; while the South Mall Theater averaged 598 patrons per day. From past information, it is known that the variance for
North Mall is 1,000; while the variance for the South Mall is 1,304. Develop a 95% confidence interval for the difference
between the average daily attendance at the two theaters.
24.16 to 39.84 (rounding: 24 to 40)