A question paper on mathmatics consists of twelve question divided into three parts . A,B and C, each containing four questions . In how many ways can an examinee answer five questions , selecting atleast one from each part.
A question paper consists of twelve questions divided into three parts, A, B and C, each containing 4 questions. In how many ways can an examine answer 5 questions by selecting at least one from each part?
Lets start by answering 1 question from each part:
Section A: 1 question has to be answered from 4 available questions. so it can be done in 4 ways.
Similarly 4 ways each for other 2 sections.
Now 3 questions are answered out of 5. There is no restriction for the remaining 2 questions. So these can be chosen from any of the remaining 9. It can be done in 9C2 ways. i.e., 36 ways.
Total number of ways: 4×4×4×36=2304.