Question

A study of three hundred teenagers found that the number of hours they spend on instant messaging sites each week is normally distributed with a mean of 13 hours. The population standard deviation is 5 hours. What is the margin of error for a 99% confidence interval?

0.743
0.334
0.320
0.413

Answer 1

0.743 is the correct answer

Answer 2

OPtion A

Explanation:

Given that a study of three hundred teenagers found that the number of hours they spend on instant messaging sites each week is normally distributed with a mean of 13 hours. The population standard deviation is 5 hours.

Std deviation = 5 hours

Sample size = 300

Hence std error of sample = 5/sqrt 300

=0.289

Margin of error = z Critical x std error

Since confidence level = 99%

Z critical = 2.58

Margin of error = 2.58 (0.289)

=0.743

Option A is right