Exercise 4 Page 329

We are told that twenty people respond yes or no to a survey question. Let a be the frequency of yes responses and b be the frequency of no responses. a: People Who Responded ``Yes'' b: People Who Responded ``No'' If a and b are the frequencies of the responses, we will find what must be true about the sum of a and b. a+ b= ? Since the frequency is the number of items in a particular group, we can say that a people responded yes and b people responded no. Since we cannot have more responses than the number of observations, the sum of these two values must be 20. a+ b=20 Now, if maybe is an option as a response, we will find what must be true about the sum of a and b. Let's consider how the maybe responses could affect our equation. Note that a+ b must be equal to 20 minus the number of maybe responses. Let's see this in a table.

This means that our sum could be any whole number between 0 and 20. We can represent this as an inequality. a+ b≤20