Question

A researcher records the following time spent sleeping per night (in hours) in a group of participants: 5.8 ± 1.8 (M ± SD). The researcher decides to categorize participants who sleep between 6 and 8 hr as moderate sleepers. What percentage of participants fell in this category?

Answer 1

Answer: 40.68 %

Explanation:

We need to find the interval between the values 0.2 and 2.2

0.2 ≤ z ≤ 2.2

Since in the standardized normal curve the mean 5.8 will be 0

Area for z values ≥ 0.2 ⇒ 0.0793 and area for z ≤ 2.2

area between 0 and 0.2 is 0.0793 ; and area between 0 to 2.2 is 0.4861

this last value includes the previous value at the left of z = 0.2

As we are looking for participants in the interval 0.2 ≤ z ≤ 2.2 we need to subtract areas 0.4861 - 0.0793 = 0.4068 express in % is 40.68 %