Chapter 4.1, Problem 20E

To determine

To explain is your sample an SRS or not.

Answer to Problem 20E

It is a stratified random sample.

Explanation of Solution

At a party, we are choose at random $3\text{ of those over 21}$ and separately choose at random $2\text{ of those under 21}$ to interview about their attitudes toward alcohol. You have given every student at the party the same chance to be interviewed. Thus, we have,

This not an SRS because each sample must containexactly $3\text{ of those over 21}$ and $2\text{ of those under 21}$ . In a SRS, any combination of students must bepossible. The sample in this problem would be considered astratified random sample. And also since we are dividing two groups by consider the age as one of thespecifications so it is not an Simple random sample it isstratified random sampling.