Answer:
0.998 is the probability that the average money spent by a sample of 40 shoppers is within $10 of the actual population mean.
Step-by-step explanation:
We are given the following information in the question:
Standard Deviation, σ = $21.51
We are given that the distribution of average money spend is a bell shaped distribution that is a normal distribution.
Formula:

We have to find:
P( average money spent is within $10 of the actual population mean.)

Calculation the value from standard normal z table, we have,

It's called the "dividend". A dividend is a number to be divided by another number. The 3 is the divisor, a number by which another number is to be divided.
The whole problem is in the picture. I Hope this helps
<span>16/20 is 80%.</span>
You find out by multiplying the denominator: 20 * 5 = 100
Then, you do the same to the numerator which is: 16 * 5 = x
So, x = 80%
Hope this helps! :D