# Statistics quiz: be familiar with statistics before you agree to do

8. Seven customers enter a clothing store and are observed to determine if they will make a purchase. The store owner states that there is a 75% chance of a customer making a purchase.  The random variable x represents a customer making a purchase.

Calculate the mean, variance and standard deviation for the number of customers that make a purchase.

Select one:

9. The length of time that it takes students to complete the entrance exam for a University is normally distributed with a population mean of µ = 120 minutes and σ = 30 minutes.

What is the probability that 1 randomly selected student will take longer than 165 minutes to complete the entrance exam?

Select one:

10. The length of time that it takes students to complete the entrance exam for a University is normally distributed with a population mean of µ = 120 minutes and σ = 30 minutes.

What is the probability that the average of 25 randomly selected students will take between 115 and 125 minutes?