1) Let X be normally distributed with mean = 10 and standard deviation = 4. a) Find P(X 0). b) Find P(X > 2). c) Find P(4 < X < 10). d) Find P(6 < X < 14).

2) The mean life span of a brand name tire is 50,000 miles. Assume that the life spans of the tires are normally distributed, and the population standard deviation () is 800 miles. a) If you select one tire, what is the probability that its life span x is less than 48,500 miles? b) If you select 100 tires, what is the probability that their mean life span x is more than 50,200 miles?

3) The distribution of the number of people in line at a grocery store has a mean 3 and variance 9. A sample of the numbers of people in line in 50 stores is taken a) Calculate the probability that the sample mean is more than 4. b) Calculate the probability the sample mean is less than 2.5 c) Calculate the probability that the sample mean is between 2.4 and 2.9 4

) During a certain week the mean gas price of gasoline in California was = $2.029 per gallon. What is the probability that the mean price x for a sample of 38 randomly selected gas stations in California

was between $2.034 and $2.044? Assume = $0.049