The principal of a high school wants to gather opinions from the parents of students at his school. He starts with the 2nd name in the Parents Teacher Association (PTA) phone handbook and then selects every 5th name in the directory. The 2nd, 7th, 12th, … names in the directory are chosen for his sample. This is an example of a/an _ sample.

The weekly amount spent by a company for travel has an approximately normal distribution with mean = $550 and standard deviation = $40. a) what is the probability that the actual weekly expense will exceed $570 for more than 20 weeks during the next year? (note: one year = 52 weeks) b) what is the probability that actual weekly expenses exceed $580 for 10 or more, but 16 or fewer weeks during the next year?