   Chapter 6, Problem 18P Essentials of Statistics for the B...

8th Edition
Frederick J Gravetter + 1 other
ISBN: 9781133956570

Solutions

Chapter
Section Essentials of Statistics for the B...

8th Edition
Frederick J Gravetter + 1 other
ISBN: 9781133956570
Textbook Problem

Information from the Department of Motor Vehicles indicates that the average age of licensed drivers is μ = 45.7 years with a standard deviation of σ = 12.5 years. Assuming that the distribution of drivers’ ages is approximately normal, a. What proportion of licensed drivers are older than 50 years old? b. What proportion of licensed drivers are younger than 30 years old?

(a)

To determine

To find: The proportion of licensed drivers are older than 50 years old.

Explanation

Given info:

The information is collected from the department of motor vehicles. It indicating that the average age of licensed drivers and it follows the normal distribution with mean of μ=45.7 years and standard deviation of σ=12.5

Calculation:

The formula for z score is,

z=Xμσ

Substitute the value 50 for X, 45.7 for μ and 12.5 for σ.

z=5045.712.5=4.312.5=0

(b)

To determine

To find: The proportion of licensed drivers are younger than 30 years old.

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