Suppose scores in a certain school test follows a normal probability distribution, with #\mu=70# and #sigma=10#. Grade A is awarded to the highest #2.5%# students. What is the dividing point between grade A & grade B?
1 Answer
Jan 30, 2018
90
Explanation:
This is really a Statistics question, although the solution is algebraic. From the definition of the "Standard Distribution Curve" we know that two standard deviations from the mean contains 95% of the total. Thus, EACH "tail" contains 2.5% of the rest. We want to know the point where the "high end tail" is 2.5%
A mean of 70 plus two standard deviations (10 + 10) is 90. Therefore, the dividing grade between an A and a B in this case would be 90.
