### Home > CCA > Chapter 10 > Lesson 10.2.3 > Problem10-59

10-59.

Delenn is re-examining the difference in backpacks among different grade levels at her school. (She previously collected data in Lesson 8.1.3.) Now she has collected a new random sample of 100 students to see if there are categorical relationships between carrying backpacks and graduating classes.

Freshmen

Sophomore

Junior

Senior

Backpack

8

16

18

19

No Backpack

3

6

14

16

TOTAL

11

22

32

35

1. Based on her sample, what percentage of students do not carry a backpack at school?

What is the total number of students at Delenn's school?
What is the total number of students who do not carry a backpack?
Use those numbers to find the percentage.

2. If a junior is chosen, what is the probability they are carrying a backpack?

Use the same method as part (a), but limit the numbers to juniors only.

3. If a student is not carrying a backpack, what is the probability they are a junior or senior?

$\frac{30}{39}$

4. Is there a relationship between graduating class and carrying a backpack at school? Show your evidence.