A set of electric toothbrush prices are normally distributed with a mean of 87 dollars and a standard deviation of
8 dollars.
What proportion of electric toothbrush prices are between 104.60 dollars and 108.20 dollars?
You may round your answer to four decimal places.

The proportion of electric toothbrush prices are between 104.60 dollars and 108.20 dollars is 0.0099

Step-by-step explanation:

A set of electric toothbrush prices are normally distributed with a mean of 87 dollars and a standard deviation of  8 dollars.

Standard deviation =

We are supposed to find proportion of electric toothbrush prices are between 104.60 dollars and 108.20 dollars i.e.P(104.60<x<108.20)

At x = 104.60

Z= 2.2

At x=108.20

Z= 2.65

Refer the z table for p value :

P(x<108.20)-P(x<104.60)=P(Z<2.65)-P(Z<2.2)=0.9960-0.9861=0.0099

Hence The proportion of electric toothbrush prices are between 104.60 dollars and 108.20 dollars is 0.0099