SOLUTION: If the average test score is 70%, how many students out of 90 are likely to get at least a B (80% or above) if the standard deviation is 10%?

Question 977918: If the average test score is 70%, how many students out of 90 are likely to get at least a B (80% or above) if the standard deviation is 10%?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
Assuming a normal distribution, this is asking how many students will be more than 1 standard deviation above the average.
It is NOT a proportion test, because the standard deviation is a function of the data and here it is given.
The probability of more than 1 SD above the average is 0.1587 or about 0.16. That translates to 14.4 students or 14 as the best answer.

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