Question: For each of the following research questions, specify whether the parameter of interest is one population mean, the population mean of paired differences, or the difference between the means of two populations.
a. Nutrition trends have changed over the years, and this may affect growth. Researchers want to know whether the mean height of 25-year-old women is the same as the mean height of 45-year-old women.
b. You plan to fly from New York to Chicago and have a choice of two flights. You are able to find out how many minutes late each flight was for a random sample of 25 days over the past few years. (You have data for both flights on the same 25 days.) You want to know whether one flight has a higher average delay (i.e., a higher population mean for the number of minutes the flight is late).