Given:
Mean of 52 minutes and a standard deviation of 5 minutes.
Solution:
According to the empirical rule: For the normal distribution, all of the data will fall within three standard deviations of the mean.
1: 68% of the data will fall within the first standard deviation from the mean.
2: 95% of the data fall within two standard deviations.
3: 99.7% of the data fall within three standard deviations.
[tex]3SD =99.7\%=\mu\pm3\sigma\\[/tex]
Therefore, the 7 intervals and their probabilities are:
1. [tex]1SD=0.68=P(47<x<57)[/tex]
2. [tex]0.95=P(42<x<62)[/tex]
3. [tex]0.997=P(37<x<67)[/tex]
4.[tex]13.5\%=P(42<x<47)[/tex]
5.[tex]13.5\%=P(57<x<62)[/tex]
6. [tex]2.35\%=P(37<x<42)[/tex]
7.[tex]2.35\%=P(62<x<67)[/tex]
