Answer:
5.48% of the people in line waited for more than 28 minutes
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the z-score of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
Mean waiting time of 20 minutes with a standard deviation of 5 minutes.
This means that 
What percentage of the people in line waited for more than 28 minutes?
The proportion is 1 subtracted by the p-value of Z when X = 28. So



has a p-value of 0.9452.
1 - 0.9452 = 0.0548.
As a percentage:
0.0548*100% = 5.48%
5.48% of the people in line waited for more than 28 minutes
A reciprocal is the inverse of a number. if you are given a whole number such as 2 or 3 or 4 or 5... etc. then you flip the number by putting a 1 as the numerator. so the reciprocal of 2 is 1/2 and for 3 it is 1/3 and 4 is 1/4... and so on...
first put your decimal in fraction form
2.5 = 2 and 5/10
= 2 and 1/2
= 5/2 ---> 2/5 (0.4) is the reciprocal of 2.5