SOLUTION: The amount of Jen's monthly phone bill is normally distributed with a mean of $78 and a standard deviation of $9. What percentage of her phone bills are between $51 and $105?

Question 1168550: The amount of Jen's monthly phone bill is normally distributed with a mean of $78 and a standard deviation of $9. What percentage of her phone bills are between $51 and $105?
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
use the calculator at http://davidmlane.com/hyperstat/z_table.html

set it to value from an area.
give it a mean of 78 and a standard deviation of 9.
select between and enter 51 in the left box and 105 in the right box.
calculator tells you that the percentage of phone bills between 51 and 105 is .9973 * 100 = 99.73%.

here are the results from the calculator.

if you need how to do it any other way, let me know what that way is and i'll see if i can help you.
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