2. The grades on a statistics midterm exam were normally distributed with a
mean of 72 and a standard deviation of 8.
a. What is the proportion of students received a B grade.
b. What is the proportion of students that failed the exam?
c. What is the grade of the 92nd percentile?
statistics - PsyDAG, Thursday, February 16, 2012 at 11:15am
Cannot answer a and b unless you know point value for B and F. Once you find the point values, use the equation below.
c. Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion (.92) for a Z score. Put Z score and other values into the equation below and solve.
Z = (score-mean)/SD