Question

In a health club, research shows that on average, patrons spend an average of 42.5 minutes on the treadmill, with a standard deviation of 5.4 minutes. It is assumed that this is a normally distributed variable. Find the probability that randomly selected individual would spent between 30 and 40 minutes on the treadmill.

a. 0.38
b. 0.69
c. 0.99
d. 0.31

Answer 1

0.3114

Option d is right

Explanation:

Let X be the time spent on a treadmill in the health club

Given that research shows that on average, patrons spend an average of 42.5 minutes on the treadmill, with a standard deviation of 5.4 minutes

Also given that X is normal

the probability that randomly selected individual would spent between 30 and 40 minutes on the treadmill.

`= P(30<x<40)= \\F(40)-F(30)\\= 0.3217-0.0103\\=0.3114`

round off to two decimals tog et

the probability that randomly selected individual would spent between 30 and 40 minutes on the treadmill is 0.31

Hence option d is right