Scores on a marketing exam are known to be normally distribu

Scores on a marketing exam are known to be normally distribute with mean and standard deviation of 60 and 20, respectively. The syllabus suggests that the top 15% of the students will get an A in the course. What is the minimum score required to get an A? Please round to an integer number.

Solution

Students grades were normally distributed with a mean of 60 and a standard deviation of 20.
15 percent of the students received grades of A. what is the minimum score needed to receive a grade of A?
Find the z-value with a right tail of 15%
invNorm(1-0.15) = 1.0364
Find the corresponding x-value using x = zs+u   where s= standard deviation

and u = mean
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x = 1.0364*20 + 60= 80.728 or approximately 80.73