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 F's?

A) 10.00
B) 2.28
C) 2.62
D) 13.59
E) 4.56