Question

Scores on a mathematics examination appear to follow a normal distribution with mean of 65 and standard deviation of 15. The instructor wishes to give a grade of ""C"" to students scoring between the 60th and 70th percentiles on the exam. What score represents the 70th percentile score on the mathematics exam?

Answer 1

72,86 ≈ 73

Explanation:

In this case we can use the normal table in which you must find the value 0.7 (in the inside) and then you should find the corresponding z value. After this you should multiply the z value by the standard deviation and then you must at to it the mean. This way you can get the score.

Another option is to use the function NORM.INV in excel where you must pass as arguments the probability (0.7), the mean (65) and standard deviation (15)