Question

The numbers of pages in the books in a library follow a normal distribution. If the mean number of pages is 180 and the standard deviation is 30 pages, what can you conclude?

About 60% of the books have fewer than 150 pages.

About 16% of the books have fewer than 150 pages.

About 95% of the books have more than 150 pages.

About 16% of the books have more than 150 pages.

Answer 1

remember that the areas under the curve go

0.1%, 2.1%, 13.6%, 34.1%, 34.1%, 13.6%, 2.1%, 0.1%

Answer 2

I would go one by one through the possible answers, with a normal distribution curve close by, and check them. I've attached a curve here.

Look at the first one. If the first choice is true, then you should get about 60% when you add up all the pieces under the curve to the left of the -1 standard deviation mark on the curve, because 150 is one standard deviation below the mean.

Answer 3

Here is a curve attached.

Answer 4

You would add starting at that mark and moving left. You're moving left because the choice says less than.