A certain type of plywood consists of five layers. The

Answer:

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.