The times of the runners in a marathon are normally distributed, with a mean of 3 hours and 50 minutes and a standard deviation of 30 minutes. What is the probability that a randomly selected runner has a time less than or equal to 3 hours and 20 minutes? Use the portion of the standard normal table below to help answer the question.

16%
32%
34%
84%

Question

The times of the runners in a marathon are normally distributed, with a mean of 3 hours and 50 minutes and a standard deviation of 30 minutes. What is the probability that a randomly selected runner has a time less than or equal to 3 hours and 20 minutes? Use the portion of the standard normal table below to help answer the question.


16%
32%
34%
84%

supercalifragalisticexspeaalli · Answer

do u still need help @Mayrapa123

math&ing001 · Answer

First you determine the z-score:
$$z=\frac{x - \mu }{\sigma} = \frac{3h20min - 3h50min }{30min} = -1$$ $\mu$ is the mean and $\sigma$ is the standard deviation.
Then from the standard normal table, you'll get that the probability is 15.87%, which rounded up makes 16%.

mayrapa123 · Answer

Thanks @math&ing001

math&ing001 · Answer

Welcome =3