JEE Mains · Maths · STD 11 - 6. permutation and combination
A test consists of \(6\) multiple choice questions, each having \(4\) alternative ans wers of which only one is correct. The number of ways, in which a candidate answers all six questions such that exactly four of the answers are correct, is
- A \(135\)
- B \(140\)
- C \(125\)
- D \(130\)
Answer & Solution
Correct Answer
(A) \(135\)
Step-by-step Solution
Detailed explanation
\(Ways ={ }^{6} C _{4} \cdot 1^{4} \cdot 3^{2} \) \(=15 \times 9 \) \(=135 \)
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