11. A hypothetical population consists of eight individuals ages 13, 14, 17, 20, 21, 22, 24, and 30 years.

What is the probability that a person in this population is a teenager?

What is the probability of selecting a participant who is at least 20 years old?

What is the probability of selecting a participant older than 30?

15. Using the unit normal table, find the proportion under the standard normal curve that lies between each of the following:

The mean and z = 0

The mean and z = 1.96

z = 1.50 and z = 1.50

z = 0.30 and z = 0.10

z = 1.00 and z = 2.00

19. A sample of final exam scores is normally distributed with a mean equal to 20 and a variance equal to 25.

What percentage of scores is between 15 and 25?

What raw score is the cutoff for the top 10% of scores?

What is the probability of a score less than 27?

What is the proportion below 13?

21. A set of scores measuring aggression is normally distributed with a mean equal to 23 and a standard deviation equal to 2.5. Find the proportion:

To the left of x = 19.0

To the right of x = 25.5

Between the mean and x = 19.0

To the left of x = 25.5

To the right of x = 19.0