1.) X is a normally distributed random variable with mean 50 and standard deviation 5. What is the probability that X will be less than 55?

a) 0.159

b) 0.023

c) 0.841

d) 0.977

2.) The 80th percentile of the standard normal (Z) distribution is .84

a) True

b) False

3.) If X is binomial with n = 5 and p = 0.05, the chance that X is at least 1 is 0.7738

a) True

b) False

4.) Which of the following variables has a binomial distribution?

a) Flipping a coin until you get 10 heads and counting the number of flips needed.

b) Both of these choices have binomial distributions.

c) Flipping a coin 10 times and counting the number of heads.

d) Neither of these choices has a binomial distribution.

5.) Suppose X = number of women in a sample of size 100 from a population that has 80% women and 20% men. X has an approximate normal distribution with mean _____ and standard deviation ______

a) 80, 4

b) 80, 16

c) 50, 5

d) None of the other choices is correct

6.) When you use the normal distribution to find a probability for a binomial random variable, which of the following is true?

a) You are making a mistake.

b) You needed np and n(1-p) to be at least 10 and you get an approximate answer.

c) None of the other choices is correct

d) You needed np and np(-p) to be less than 10.