A survey was conducted to determine whether hours of sleep per night are independent of age. A sample of individuals was asked to indicate the number of hours of sleep per night with categorical options: fewer than 6 hours, 6 to 6.9 hours, 7 to 7.9 hours, and 8 hours or more. Later in the survey, the individuals were asked to indicate their age with categorical options: age 39 or younger and age 40 or older. Sample data follow. Age Group
Hours of Sleep 39 or younger 40 or older
Fewer than 6 38 36
6 to 6.9 61 58
7 to 7.9 76 74
8 or more 65 92
(a) Conduct a test of independence to determine whether hours of sleep are independent of age.
(b) What is your estimate of the percentages of individuals who sleep fewer than 6 hours, 6 to 6.9 hours, 7 to 7.9 hours, and 8 hours or more per night?

Sleep hours per night is independent.

Step-by-step explanation:

Given the data:

Hours of Sleep 39 or younger 40 or older

> 6 38 36

6 to 6.9 _ 61 58

7 to 7.9 __76 74

8 or more 65 92

The Chisquare statistic is to be used to perform the analysis :

The hypothesis :

H0: Sleep hours per night is independent

H1: Sleep hours per night is not independent

χ² = (observed - Expected)² / Expected

To save computation time. We could use a Chisquare calculator to perform the analysis :

The test statistic = 4.0061

The degree of freedom = (row - 1) * (column - 1)

Degree of freedom = (4-1)*(2-1) = 3*1 = 3

The Pvalue = 0.261

Since, Pvalue > α ; We fail to reject the H0 ;and conclude that sleep hours per night is independent.

total ___%

> 6 38 36__ 74 __ 14.8

6 to 6.9 _ 61 58 __ 119 __23.8

7 to 7.9 __76 74___150__30

8 or more 65 92___157__31.4

240 _260__500_100

+25 = x

step-by-step explanation:

here x is the hypotenuse of a right triangle whose legs are 7 and 24.   by the pythagorean theorem, 7² + 24² must equal x²:

x² = 49 + 576 = 625.   thus, x = +√625 = +25 = x