Question

1. on a race track, you take a random sample of the speed of 40 cars and determine that their average speed is 94 mph. which statement is true?

a. you conclude that the average speed of all the cars is close to 94 mph.
b. you conclude that the speed of all cars on this track is exactly 94 mph.
c. you conclude that the average speed of all cars on this track is close to 94 mph.
d. you conclude that the speed of more than half of the cars on this track is more than 94 mph.

Explanation:

Step1: Understand sampling concept

A sample average is an estimate of the population average.

Step2: Analyze each option

• Option a: A sample of 40 cars' average speed of 94 mph is an estimate of the average speed of all cars. But "all cars" without context of the track is too general.
• Option b: A sample average doesn't mean the speed of all cars is exactly the same as the sample average. There is variability.
• Option c: Since we took a random sample of cars on the track and got an average of 94 mph, we can conclude that the average speed of all cars on this track is close to 94 mph. This is the correct use of sample - population relationship.
• Option d: The sample average doesn't give information about the speed of more than half of the cars being above or below the sample average.

Answer:

c. You conclude that the average speed of all cars on this track is close to 94 mph.