JEE Mains · Maths · STD 11 - 6. permutation and combination
In an examination, there are \(5\) multiple choice questions with \(3\) choices, out of which exactly one is correct There are \(3\) marks for each correct answer, \(-2\) marks for each wrong answer and \(0\) mark if the question is not attempted. Then, the number of ways a student appearing in the examination gets \(5\) marks is. . . . . ... . .
- A \(45\)
- B \(40\)
- C \(48\)
- D \(55\)
Answer & Solution
Correct Answer
(B) \(40\)
Step-by-step Solution
Detailed explanation
\(x _{1}+ x _{2}+ x _{3}+ x _{4}+ x _{5}=5\) Only one possibilities \(3,3,3,-2,-2\) Number of ways is \(=\frac{5 !}{3 ! 2 !} \times 2 \times 2=40\)
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