A student has 5 courses to take from Mathematics and physics. There are 4 courses in Mathematics and 3 in Physics which he can choose his courses so that he takes exactly two courses in Physics?

A.
48 
B.
12 
C.
10 
D.
7
Correct Answer: Option B
Explanation
Mathematics = (^{4} C_{3} = 4)
Physics = (^{3} C_{2} = 3)
(therefore) He can choose in 4 x 3 = 12 ways.