Question

Suppose the number of gallons of gasoline per day used by a car is normally distributed with a mean of 2.2 gallons and a standard deviation of 1.2 gallons.

What is the difference in gallons per day used by a car with a z-score of 3 and another car that has a z-score of 0?




A. 1.2

B. 2.6

C. 3.6

D. 4.6

Answer 1

Hello!

The mean is 2.2 and the standard deviation is 1.2

You count down from 2.2 by 1.2 till you get to 0

2.2 - 1.2 = 1

1 - 1.2 = -0.2

So it has a deviation of just under 2

Now count up to 3

2.2 + 1.2 = 3.4

So it has a deviation of around 0.8

The answer is B. 2.6

Hope this helps!