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.

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

   Hint (a):

   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?

   Hint (b):

   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?

   Answer (c):

   $\frac{30}{39}$

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

   Hint (d):

   Create a relative frequency table to help you answer this question.
   Look at the table you created.
   Which classes have a greater frequency of carrying a backpack?