In 2010, Apple introduced the iPad, a tablet-style computer that its former CEO Steve Jobs called a "a truly magical and revolutionary product'' (CNN, January 28, 2010). Suppose you are put in charge of determining the age profile of people who purchased the iPad in the U.S. Explain in detail the following sampling strategies that you could use to select a representative sample.

a. Simple random sampling

b. Stratified random sampling

c. Cluster sampling L01