CPM Homework Help : INT1 Problem 11-6

Delenn is re-examining the difference in backpacks among different grade levels at her school. 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	Totals
Backpack	$8$	$16$	$18$	$19$	$\textbf{61}$
No Backpack	$3$	$6$	$14$	$16$	$\mathbf{39}$
Totals	$\mathbf{11}$	$\mathbf{22}$	$\mathbf{32}$	$\mathbf{35}$	$\mathbf{100}$

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.
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.
If a student is not carrying a backpack, what is the probability they are a junior or senior?
Answer (c):
$\frac{30}{39}$
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?