Question

Chapter 7:

The mean mean gas mileage for a hybrid car is 57 milers per gallon. Suppose that the gasoline mileage is approximately normal distributed with a standard deviation with 3.5 milers per gallon. (A) what proportion of hybrids get over 62 milers per gallon? B.) What proportion of hybrids gets 52 milers per gallon or less? C.) what proportion of hybrids gets between 59 and 62 miles per gallon? D.) What is the probability that a randomly selected hybrid gets less than 45 miles per gallon?

A.) The proportion of hybrids that gets over 62 miles per gallon is ____

(Round to four decimal places as needed).

B.) The proportion of hybrids that gets 52 miles per gallon or less is ____

(Round to four decimal places as needed).

C) The proportion of hybrids that gets between and 62 miles per gallon is ____

(Round to four decimal places as needed).

D.) The probability that a randomly selected hybrid gets less than 45 miles per gallon is ___

(Round to four decimal places as needed).

Answer 1

Since the distribution us normal hence Z statistic is used to calculate the proportion so,

a} P(X>62)

Z at X=62

So, P(X>62)=P(Z>1.43)

which is calculated using Z table shown below as

=0.0764

b) Similarly

P(X=<52)

Z at 52

P(X<52)=P(Z<-1.43)

=0.0764

c) This question is mill one element ,   between ? and 62 miles per gallon

d) P(X<45)

Z at X=45

P(X<45)=P(Z<-3.43)

=0.0003