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:
[tex]z_{score} = \displaystyle\frac{x-\mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
We have to find:
P( average money spent is within $10 of the actual population mean.)
[tex]= P( z \leq \displaystyle\frac{10\times \sqrt{40}}{21.51}}) = P(z \leq 2.94)[/tex]
Calculation the value from standard normal z table, we have,
[tex]P(z \leq 2.94) = 0.998[/tex]