The time per week a student uses a lab computer is normally distributed, with a mean of 6.2 hours and a standard deviation of 0.9 hour. A student is randomly selected.

Question

a. Find the probability that a student uses a lab computer less than 4 hours per week.

b. Find the probability that a student uses a lab computer between 5 and 7 hours per week.

Answer 1

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions/probabilities related to the Z scores.

Answer 2

2.376

Answer 3

25