The amount of time workers spend commuting to their jobs each day in a large metropolitan city has a mean of 70 minutes and a standard deviation of 20 minutes. Assuming the distribution of
Commuting times is known to be moundshaped and symmetric, what percentage of these
Commuting times are between 50 and 110 minutes?
A)approximately 81.5%
B)approximately 68%
C)approximately 97.5%
D)approximately 95%

Question

Quizplus · Accepted Answer

Using the empirical rule, approximately 68% of the data falls within one standard deviation of the mean, and approximately 95% of the data falls within two standard deviations of the mean. In this case, one standard deviation is 20 minutes, so 50 minutes is one standard deviation below the mean and 110 minutes is one standard deviation above the mean. Therefore, approximately 68% of the commuting times are between 50 and 110 minutes.

The Amount of Time Workers Spend Commuting to Their Jobs