Question

Question 40: A study is conducted to find out the average number of students' self-study hours a week. The results of a pilot survey show that the average number of hours of self-study is 18 hours with a standard deviation of 3 hours. With 98% confidence, if you want the error to be estimated to be zero + 0.5 hours, how many students should you choose to investigate?

Answer 1

#Given:

mean=18

standard deviation==3

Margin of error=0.5

#=1-c%=1-0.98=0.02

Z/2=Z0.02/2=Z0.01=2.326

#value Z0.01 is obtain from standard normal table

Sample size=n

n=(Z/2*/ME)^2

n=(2.3263*3/0.5)^2=194.82

#Sample size =195

# 195  students should you choose to investigate