College

People spend an average of 5 hours a day on their computers with a standard deviation of 1.25 hours.

1. What proportion of people spends 4 hours or less on their computers per day?
__%. (Give as a percent rounded to the nearest hundredths place)

2. If 100,000 people are chosen randomly, about how many are expected to spend 4 hours or less on their computers?
__ people. (Round to a whole number)

Answer :

The proportion of people spending 4 hours or less on their computer per day is approximately 21.19%. Out of 100,000 people, approximately 21,190 are expected to spend 4 hours or less on their computers.

Part 1: Proportion of people spending 4 hours or less

To solve this, we need to convert the time (4 hours) into a z-score.

z = (X - μ) / σ

z = (4 - 5) / 1.25 = -0.8

Using a z-table, we find that the area to the left of z = -0.8 is approximately 0.2119.

So, 21.19% of people spend 4 hours or less on their computers.

Part 2: Number of people spending 4 hours or less out of 100,000

If 21.19% of people spend 4 hours or less, then out of 100,000 people, the number of people spending 4 hours or less is:

0.2119 * 100,000 = 21,190 people.

Approximately 21,190 people out of 100,000 are expected to spend 4 hours or less on their computers.