The table gives 20 years of data on the number of students in a particular school who dropped out in the ninth grade. A sample is taken to include only the last 3 years of this data. With this information, calculate both the population mean and the sample mean for ninth-grade dropouts per year.

4.35 and 5.33

the revenue of the fitness center, y, is the product of two factors: the number of members and the fee paid by each member. there are 320 members now, but number of members goes down by 10 for each $5 increase in fees, so if x is the number of $5 price increases then members is equal to (320 - 10x). since the fee is currently $45, and the fee increases by $5 for every price bump x, the fee is given by (45 + 5x). so, revenue y is given by y = (320 - 10x)(45 + 5x).