In January 2003, the American worker spent an average of 77 hours logged on to the internet while at work (CNBC, March 15, 2003). As- sume the times are normally distributed and that the standard devia- tion is 20 hours. (a) What is the probability that in January 2003 a randomly selected worker spent fewer than 50 hours logged on to the internet? (b) What percentage of workers spent more than 100 hours? (c) What percentage of workers spent between 50 and 100 hours? (d) A person is classified as a heavy user if she or he is in the upper 20% of usage. In January 2003, how many hours did a worker have to be logged on in order to be considered a heavy user?

A First Course in Probability (10th Edition)
10th Edition
ISBN:9780134753119
Author:Sheldon Ross
Publisher:Sheldon Ross
Chapter1: Combinatorial Analysis
Section: Chapter Questions
Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...
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Probability: Distributions.

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In January 2003, the American worker spent an average of 77 hours
logged on to the internet while at work (CNBC, March 15, 2003). As-
sume the times are normally distributed and that the standard devia-
tion is 20 hours.
(a) What is the probability that in January 2003 a randomly selected
worker spent fewer than 50 hours logged on to the internet?
(b) What percentage of workers spent more than 100 hours?
(c) What percentage of workers spent between 50 and 100 hours?
(d) A person is classified as a heavy user if she or he is in the upper
20% of usage. In January 2003, how many hours did a worker
have to be logged on in order to be considered a heavy user?
Transcribed Image Text:In January 2003, the American worker spent an average of 77 hours logged on to the internet while at work (CNBC, March 15, 2003). As- sume the times are normally distributed and that the standard devia- tion is 20 hours. (a) What is the probability that in January 2003 a randomly selected worker spent fewer than 50 hours logged on to the internet? (b) What percentage of workers spent more than 100 hours? (c) What percentage of workers spent between 50 and 100 hours? (d) A person is classified as a heavy user if she or he is in the upper 20% of usage. In January 2003, how many hours did a worker have to be logged on in order to be considered a heavy user?
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