4. If 80% of job applicants can pass a computer literacy test, for a smaple of 150 applicants:
a) Explain why this a binomial distribution. 4 requirements from the section
b) Find the mean, variance, and standard deviation of the number of people who pass the examination. Mean=120 people, variance=24 people^2, stdev=4.89 people
5. A survey found that the mean amount of time a driver in Boston spends to find a parking space is 53 hours per year. Assume the variable is normally distributed and the standard deviation is 6 hours:
a) If an individual driver from Boston is randomly selected, find the probability they will spend between 52 and 55 hours per year trying to find a parking space. 0.1967
b) If a sample of 30 drivers is randomly selected, find the probability that the mean of the sample will be between 52 and 55 hours. 0.7854
c) Why is the answer to part a) smaller than the answer to part b)? individual vs. sample.
6. The average charitable contribution itemized per income tax return in Pennsylvania is $792. Suppose that the distribution of contributions is normal with a standard deviation of $103. Find the limits for the middle 60% of contribution. ($705.31, $878.69)
