The following are the duration in minutes of a sample of long-distance phone calls.
Relative
Time (in Minutes) Frequency
0 but less than 2 0.30
2 but less than 4 0.20
4 but less than 6 0.25
6 but less than 8 0.10
8 but less than 10 0.07
10 but less than 12 0.05
12 or more 0.03
What is the cumulative relative frequency for the percentage of calls that lasted 8 minutes or more?
0.08
0.25
0.15
0.75
0.25
The cumulative relative frequency for calls that lasted 8 minutes or more would be the sum of the relative frequencies for 8 but less than 10 minutes and 10 but less than 12 minutes, which are 0.07 and 0.05 respectively.
0.07 + 0.05 = 0.12
Therefore, the cumulative relative frequency for calls that lasted 8 minutes or more is 0.12.