A final examination requires that a student answer any 4 out of 6 questions. In how many ways can this be done?
A
15
B
20
C
30
D
45
Verified Correct Answer: A.
Step-by-Step Mathematical Solution
The question will be answered in
\(^6C_4 = \frac{6!}{(6-4)!4!}\)
=\(\frac{6!}{2!4!}\)
=\(\frac{6\times5\times4!}{2\times1\times4!}\) = 15ways.
Source: Myschool Past Questions Archive (Record #8623)