CPM Homework Help : ACC7 Problem 7-111

Researchers have determined that teenagers’ memories are negatively affected by getting less than $10$ hours of sleep. Being good scientists, the math students at North Middle School were skeptical, so they did their own study. They asked $300$ students to memorize $10$ objects. The next day, each student was asked how much sleep they got and then was asked to list the ten items. The results are below.

Remembered all $\mathbf{10}$ items?

	Yes	No	TOTAL
Less than $7$ hours sleep	$6$	$149$	$155$
$\mathbf{7}$ to $\mathbf{9}$ hours sleep	$11$	$109$	$120$
At least $\mathbf{10}$ hours sleep	$5$	$20$	$25$
TOTAL	$22$	$278$	$300$

Make a conditional relative frequency table to determine if there is an association between hours of sleep and memory.

Hint 1:

In order to make a conditional relative frequency table, you must first decide which variable is independent and which is dependent.

Answer:

Remembering depends on how many hours of sleep a student gets so the independent variable is hours of sleep.

Hint 2:

The frequencies should be calculated based on row totals.

Partial Answer:

	Yes	No
	Remembered all 10 items?
Less than $\mathbf{7}$ hours sleep	$\mathbf{3.9\%}$
$\mathbf{7}$ to $\mathbf{9}$ hours sleep		$\mathbf{90.8\%}$
At least $\mathbf{10}$ hours sleep