Measures of Center and Spread

Question

For a 4-unit class like Statistics, students should spend average of 12 hours studying for the class. A survey was done on 25 students, and the distribution of total study hours per week is bell-shaped with a mean of 14 hours and a standard deviation of 3.2 hours.

Use the Empirical Rule to answer the following questions.

a) 68% of the students spend between  hours and  hours on Statistics each week.

b) 95% of the students spend between  hours and  hours on Statistics each week.

c) 99.7% of the students spend between  hours and  hours on Statistics each week.

Answer 1

We'll need to assume that the population is normally distributed for this problem.

The empirical rule tells use that approximately 68% of students in a normally distributed population are within +- 1SD of the mean, 95% within +- 2SD of the mean, and 99.7% +- 3 SD of the mean.

So, you've been given estimates of the population mean and population standard deviation