Question 1205159
mean is 48 minutes.
standard deviation is 4 minutes.
36 minutes is 12 minutes less than 48 minutes.
divide that by 4 and you get 3 standard deviations.
60 minutes is 12 minutes greater than 48 minutes.
divide that by 4 and you get 3 standard deviations.
your percentage will be plus or minus 3 standard deviations from the mean.
by the empirical rule, that represents 99.7% of the area under the normal distribution curve.
therefore, 99.7% of her commutes will be between 36 and 60 minutes.
here's a reference on the empirical rule.
<a href = "https://online.stat.psu.edu/stat800/lesson/2/2.2" target = "_blank">https://online.stat.psu.edu/stat800/lesson/2/2.2</a>