Use the following information for following questions . The average travel time to work for a person living and
working in Kokomo, Indiana is 17 minutes. Suppose the standard deviation of travel time to work is 4.5 minutes and
the distribution of travel time is approximately normally distributed.
-Approximately what percentage of people living and working in Kokomo have a travel time to work that is less than 12.5 minutes? Round to the nearest whole percent.
A)16%
B)68%
C)5%
D)84%.

Question

Quizplus · Accepted Answer

To find the percentage of people with a travel time less than 12.5 minutes, we calculate the Z-score: $Z = \frac{X - \mu}{\sigma} = \frac{12.5 - 17}{4.5} = -1$. Looking up a Z-score of -1 in a standard normal distribution table or using a calculator, we find that approximately 16% of the area under the curve is to the left of this Z-score, which corresponds to the percentage of people with a travel time less than 12.5 minutes.

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