SOLUTION: A teacher gives a test and gets normally distributed results with a mean of 50 and a standard deviation of 10. If the top 10% will receive an A and the bottom 10% will receive an F

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Question 251238: A teacher gives a test and gets normally distributed results with a mean of 50 and a standard deviation of 10. If the top 10% will receive an A and the bottom 10% will receive an F, find the minimum score for a letter grade of A and the maximum score fo the letter grade of F.

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
mean is 50.
Standard Deviation is 10.

Top 10% get an A.
Bottom 10% get an F.

Based on normal distribution, you can use the Z-Table Calculator to find the percentages of the population that fall under each category.

Any score below 37.1845 will get an F.

Any score above 62.8155 will get an A.

Select the following link to access the z-table calculator.

http://davidmlane.com/hyperstat/z_table.html

you select the bottom graph.
enter a mean of 50
enter a standard deviation of 10
enter a shaded area of .1
select below to get the bottom 10%
select above to get the top 10%

the graph will show you the area you picked.