Chapter 11.4, Problem 22E

To determine

To correct and describe the error.

Answer to Problem 22E

This is the correct two-way table with joint relative frequencies.

		Participate in Fundraiser
		Yes	No
Class	Freshman	0.38	0.18
	Sophomore	0.25	0.19

Explanation of Solution

Given information :

The information provided in the two-way table.

Joint relative frequencies are found out by dividing each joint frequency by the total number of observations in the two-way table.

Here, the joint frequencies are divided by the marginal frequencies instead.

Total number of observations is

  $187+85+123+93=488$

For instance, Freshman who participated in the fundraiser is:

  $\frac{187}{488}\approx 0.38$

The correct calculation is

		Participate in Fundraiser
		Yes	No
Class	Freshman	$\frac{187}{488}\approx 0.38$	$\frac{85}{488}\approx 0.18$
	Sophomore	$\frac{123}{488}\approx 0.25$	$\frac{93}{488}\approx 0.19$