Question

According to Common Sense Media, U.S. teenagers spend an average of 9 hours a day on media, including cell phones, TV and internet. Assume the standard deviation is 1 hour. According to the empirical rule, approximately what percent of U.S. teenagers spend between 7 and 11 hours a day on media?

Answer 1

Solution:

Given a bell shaped distribution( NORMAL DISTRIBUTION) with

= 9

= 1

Now ,

7 = 9 - 2 = - (2 * )

11 = 9 + 2 = + (2 * )

According to the empirical rule , 95% of the data lie within 2 standard deviations from the mean

i.e. within - 2 and + 2

So , answer is

According to the empirical rule, approximately 95% of U.S. teenagers spend between 7 and 11 hours a day on media.