Question

70 adults with gum disease were asked the number of

times per week they used to floss before their
diagnoses. The (incomplete) results are shown below:
(frequency of 6, relative frequency of 4, and cumulative frequency of 5 are blank)
# of
times
floss
per
week
0
1
2
3
4
5
Frequency
6
7
4
11
15
11
6
7
Relative
Frequency
6
0.1571
0.2143
0.1571
0.0857
0.1

Cumulative
Frequency
0.1429
64
0.0857
70
a. Complete the table (Use 4 decimal places when
applicable)
4
15
30
41
47
b. What is the cumulative relative frequency for
flossing 3 times per week?
%​

Answer 1

a. To complete the table:

# of times floss per week Frequency Relative Frequency Cumulative Frequency

0 6 0.0857 6

1 7 0.1 13

2 4 0.0571 17

3 11 0.1571 28

4 15 0.2143 43

5 11 0.1571 54

6 6 0.0857 60

7 7 0.1 67

Explanation:

b. To find the cumulative relative frequency for flossing 3 times per week, we need to add up the relative frequencies for all values of flossing less than or equal to 3.

Cumulative relative frequency for flossing 3 times per week:

= relative frequency for flossing 0 times per week + relative frequency for flossing 1 time per week + relative frequency for flossing 2 times per week + relative frequency for flossing 3 times per week

= 0.0857 + 0.1 + 0.0571 + 0.1571

= 0.4

Therefore, the cumulative relative frequency for flossing 3 times per week is 40%.