Answer:
99.7% of customers have to wait between 8 minutes to 30 minutes for their food.
Step-by-step explanation:
We are given the following in the question:
Mean, μ = 18 minutes
Standard Deviation, σ = 4 minutes
We are given that the distribution of amount of time is a bell shaped distribution that is a normal distribution.
Empirical Formula:
- Almost all the data lies within three standard deviation from the mean for a normally distributed data.
- About 68% of data lies within one standard deviation from the mean.
- About 95% of data lies within two standard deviations of the mean.
- About 99.7% of data lies within three standard deviation of the mean.
Thus, 99.7% of the customers have to wait:

Thus, 99.7% of customers have to wait between 8 minutes to 30 minutes for their food.
Isolate the variable by dividing each side by factors that don't contain the variable.
Exact Form:
m
=
√
130
10
,
−
√
130
10
m
=
130
10
,
-
130
10
Decimal Form:
m
=
1.14017542
…
,
−
1.14017542
…
Answer: (D) 2.394 * 10^-1
Step-by-step explanation:
(4.2 * 10^-1) (5.7 * 10^-1)
= 2.394 * 10^-1