10. A value that is two standard deviations below the mean will have a z-score of____________.

17)

A normal population has mean = 20 and standard deviation = 4.

a. What proportion of the population is less than 18?

b. What is the probability that a randomly chosen value will be greater than 25?

21)

A normal population has mean = 47 and standard deviation = 3.

a. What proportion of the population is between 40 and 50?

b. What is the probability that a randomly chosen value will be between 50 and 55?

8) If the statement is false, rewrite it as a true statement.

As the sample size increases, the sampling distribution of x becomes more and more skewed.

10. A sample of size 126 will be drawn from a population with mean 26 and standard deviation 3

a. Find the probability that x will be between 25and 27.

b. Find the 55th percentile of x.

16. A sample of size 42 will be drawn from a population with mean 52 and standard deviation 9.

a. Is it appropriate to use the normal distribution to find probabilities for x?

b. If appropriate find the probability that x will be between 53and 54.

c. If appropriate find the 45th percentile of x.