# Chapter 12 - Data Analysis and Probability - 12-2 Matrix Multiplication - Practice and Problem-Solving Exercises - Page 736: 21

A.Cumulative frequency: B.70%

#### Work Step by Step

A. Cumulative frequency is the total of a frequency and all frequencies so far. For example, the cumulative frequency for 1:21-2.41 is 2 because the previous frequencies are 2 and 0 so cumulatively it is 2. For 2:42-4:02 is 7 because the previous frequencies are 5,2 and 0 so cumulatively it is 12. B. There are 10 songs and 7 of those are under 4 minutes: So divide 7 and 10 to find the percent of songs under 4 minutes: 7 $\div$10=0.7=70%. 70% of songs are under 4 minutes.

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