In a Class of 200 Students, Bill's Mark Corresponded to a Z-Score

Multiple Choice

In a class of 200 students, Bill's mark corresponded to a z-score of 1 and Tom's mark corresponded to a z-score of 2. If the distribution of marks was bell-shaped ('normal') than the number of students with a
Grade between Bill's mark and Tom's mark is closest to

A) 5
B) 10
C) 20
D) 30