Lube-Tech is a major chain whose primary business is performing lube and oil changes for passenger vehicles. The national operations manager has stated in an industry newsletter that the mean number of miles between oil changes for all passenger cars exceeds 4,200 miles. To test this, an industry group has selected a random sample of 100 vehicles that have come into a lube shop and determined the number of miles since the last oil change and lube. The sample mean was 4,278 and the standard deviation was known to be 780 miles. Based on a significance level of 0.10, the critical value for the test is approximately z = 1.28.

Question

Quizplus · Accepted Answer

Given the sample mean, known standard deviation, and the significance level, the calculation for the z-score aligns with standard statistical methods for hypothesis testing, making the critical value of approximately z = 1.28 reasonable for a one-tailed test at the 0.10 significance level.

Lube-Tech Is a Major Chain Whose Primary Business Is Performing