SOLUTION: A national achievement test has a normal distribution, a mean of 1000, and a standard deviation of 100. What percent, to the nearest whole percent, of the students taking the te

Algebra ->  Probability-and-statistics -> SOLUTION: A national achievement test has a normal distribution, a mean of 1000, and a standard deviation of 100. What percent, to the nearest whole percent, of the students taking the te      Log On


   

Question 306856: A national achievement test has a normal distribution, a mean of 1000, and a standard deviation of 100.
What percent, to the nearest whole percent, of the students taking the test scored above 800?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Find the z score.
z=%28x-xave%29%2Fsigma
z=%28800-1000%29%2F100
z=-2
At z=-2, the area under the normal distribution curve is 0.02275.
That means that 2.275% scored 800 or below.
The total area under the curve equals 1.
So subtract the value for z=-2 from 1 to get the % that scored over 800.
1-0.02275=0.97725
To the nearest percent 98% of students scored over 800.