The numbers of hours worked (per week) by 400 statistics students are shown below.

Number of hours Frequency

0 - 9 20

10 - 1980

20 - 29 200

30 - 39 100

1. The relative frequency of students working 9 hours or less

a. is 20

b. is 100

c. is 0.95

d. 0.05

2. The percentage of students working 19 hours or less is

a. 20%

b. 25%

c. 75%

d. 80%