A Student Asked a Statistics Professor If Grades Were Marked

Multiple Choice

A student asked a statistics professor if grades were marked "on the curve." The professor decided
To give the student a project to determine if last year's statistics grades were normally distributed.
The professor told the student that last year's mean mark was 70 with a standard deviation of 10
And to use the following results.
What is the expected number of grades above B?

A) 18.25
B) 20.00
C) 13.59
D) 15.87
E) 15.63