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Get Full Access to Statistics For Engineers And Scientists - 4 Edition - Chapter 4 - Problem 8se
Get Full Access to Statistics For Engineers And Scientists - 4 Edition - Chapter 4 - Problem 8se

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# A certain type of plywood consists of five layers. The

ISBN: 9780073401331 38

## Solution for problem 8SE Chapter 4

Statistics for Engineers and Scientists | 4th Edition

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Problem 8SE

Problem 8SE

A certain type of plywood consists of five layers. The thicknesses of the layers are independent and normally distributed with mean 5mm and standard deviation 0.2 mm.

a. Find the mean thickness of the plywood.

b. Find the standard deviation of the thickness of the plywood.

c. Find the probability that the plywood is less than 24 mm thick.

Step-by-Step Solution:

Step 1 of 3:

In this question we have asked to find the mean and standard deviation of the thickness of a piece of plywood which is composed of five layers.

Given data:

The thickness of layer has mean of  5 mm and standard deviation of 0.2 mm.

(a)

Let is the thickness of  the five layers and we will consider thickness as a  independent random variables.

Then total thickness of the layers can be written like this  which is a special case of linear combination.

So we can write the mean of sum as follows

………….(1)

We have asked to find the mean thickness of the plywood.

So we can write equation 1 as  ……………(2)

Put the value of mean into equation 2

= 25mm

Hence the mean thickness of the plywood is 25 mm.

Step 2 of 3

Step 3 of 3

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