Question

The amount of time it takes a student from school A to do a math activity follows the Normal distribution with a mean of 25 minutes and a standard deviation of 5 minutes. Students at school B complete a math activity with a mean time of 20 minutes and have a standard deviation of 8 minutes.

a.) If we take a random student from School A and a random student from School B. What is the expected difference in their minutes?

b.) What is the standard deviation of the difference of their minutes?

Answer 1

a.) The expected difference in their minutes is 25 - 20 = 5 minutes.

b.) To find the standard deviation of the difference, we can use the formula for the standard deviation of the difference between two normally distributed random variables:

sqrt(sd_1^2 + sd_2^2) = sqrt(5^2 + 8^2) = sqrt(25 + 64) = sqrt(89) = 9.43 minutes.