To qualify as a contestant in a race a runner have to be in the fastest 16% of all applicants the running times are normally distributed with a mean of 61 min and a standard deviation of 6 min to the nearest minute what is the qualifying time for the race

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?