Many, many snails have a one-mile race, and the time it takes for them to finish is approximately normally distributed with mean 50 hours and standard deviation 6 hours.
For the following questions, use the normal chart and the method in class. The correct procedure results in precisely the required accuracy.
The percentage of snails that take more than 60 hours to finish is %.
The relative frequency of snails that take less than 60 hours to finish is
The proportion of snails that take between 60 and 67 hours to finish is
The probability that a randomly-chosen snail will take more than 76 hours to finish (to four decimal places) is
To be among the 10% fastest snails, a snail must finish in at most hours.
The most typical 80% of snails take between and hours to finish.