Give the name of the kind of sampling that was most likely used in each of the following cases:

a. a Wall Street Journal poll of 2,000 people to determine the president’s approval rating

b. a poll taken of each of the General Motors (GM)

dealerships in Ohio in December 2008 to determine an estimate of the average number of 2008-model Chevrolets not yet sold by GM dealerships in the United States

c. a quality assurance procedure within a Frito-Lay manufacturing plant that tests every 1,000th bag of Fritos Corn Chips produced to make sure the bag is sealed properly.

d. a sampling technique in which a random sample from each of the tax brackets is obtained by the Internal Revenue Service to audit tax returns