200 LATTC students are asked how many hours they spend studying per week. The result as show below.

Hours per week Frequency Relative Frequency

0 - 2 10 5%

3 - 5 20 10%

6 - 8 50 ?

9 - 10 100 50%

11 - 12 20 10%

Find the missing relative frequency.

Identify the class width.

What percent of the respondents studiedat least9 hours per week?

What percent of the respondents studiedat most5 hours per week?