A car company is interested in testing to see whether the mean miles that a car engine will last without changing oil is the same or different depending on which brand of oil is used. The engineers also wish to control for the type of transmission (manual or automatic) that is used. To conduct this test, the car company obtains enough engines so that all four oil brands can be tested in a design that involves no replication. Based on this information, how many engines will be needed to conduct the test?
A) 4
B) 8
C) One for each oil type
D) One for each factor in the study

Question

Quizplus · Accepted Answer

The test involves four oil brands and two types of transmission (manual or automatic), with no replication. Therefore, for each oil brand, there needs to be one engine with a manual transmission and one with an automatic transmission, totaling 4 oil brands * 2 transmission types = 8 engines.

A Car Company Is Interested in Testing to See Whether