Among patients at a local fertility clinic, in-vitro fertilization (IVF) is a popular treatment for achieving pregnancy. Suppose that 250 past patients of the clinic are randomly selected from the much larger population of all past patients receiving IVF. Among these patients, the average number of IVF cycles the patients went through was 2.2 cycles, with an SD of 1.8 cycles. (We are not keeping track here of whether patients became pregnant, only how many cycles they went through at the clinic.)

(a) Consider all the past patients of this clinic receiving IVF. The average number ofcycles these patients received is estimated to be about _______ cycles, with anestimated standard error of _______ cycles.

(b) Find a 90% confidence interval for the average number of cycles among all past patients receiving IVF. Answer: ( __________, __________)

(c) Which of the following is well-approximated by the normal curve in this problem? (Check all that apply.)

The histogram of the number of cycles given by patients in the sample

The histogram of the number of cycles if we had asked everyone in the population

The probability histogram of the sample average number of cycles