Since airlines began charging for checked luggage, more passengers use carry-on bags to avoid the extra fee. For those who check luggage, the wait at the baggage carousel while jostling with other...

Since airlines began charging for checked luggage, more passengers use carry-on bags to avoid the extra fee. For those who check luggage, the wait at the baggage carousel while jostling with other passengers can be long and infuriating. A study was conducted to determine whether there is a relationship between the flight time (x, in hours) and the amount of time for a bag to arrive from a plane to the carousel (y, in minutes). A random sample of arriving flights at the Denver International Airport was obtained and the flight time and baggage time were recorded for each.

Twenty-one adults were selected at random for a study of the effect of castor oil on the immune system. Participants took a certain amount of castor oil (x, in milliliters) each day for three months. At the end of this regimen, the white blood cell count was measured (y, thousands of cells per microliter of blood) for each person. Analyze these data using any appropriate methods to determine whether there is a significant linear relationship between the amount of castor oil consumed and the number of white blood cells. Check the relevant assumptions. Assume that the more white blood cells, the stronger the immune system, and draw a conclusion about the effect of castor oil on the immune system.