Question

a study of 900 working women showed that their feelings changed throughout the day. the line graph shows 15 different times in a day and the average level of happiness for the women at each time. based on the information given by the graph, represent the set using the roster method. \\{x | x is a time of the day when 3 < average level of happiness < 4\\} choose the correct answer below. \\(\boldsymbol{\text{a. } \\{20, 21\\}}\\) \\(\boldsymbol{\text{b. } \\{12, 20\\}}\\) \\(\boldsymbol{\text{c. } \\{12, 20, 21\\}}\\) \\(\boldsymbol{\text{d. } \\{20\\}}\\)

Explanation:

Step1: Identify target happiness range

We need times where $3 < \text{happiness} < 4$.

Step2: Match times to range

Check the line graph:

• Time 12: Happiness is between 3 and 4
• Time 20: Happiness is between 3 and 4
• Time 21: Happiness is between 3 and 4

Step3: Compile roster set

Collect all qualifying times into a set.

Answer:

C. {12, 20, 21}