WBJEE · Maths · Permutation Combination
On the occasion of Dipawali festival each student of a class sends greeting cards to others. If there are 20 students in the class. the number of cards sends by students is
- A \({ }^{20} \mathrm{C}_{2}\)
- B \({ }^{20} \mathrm{P}_{2}\)
- C \(2 \times{ }^{20} \mathrm{C}_{2}\)
- D \(2 \times{ }^{20} \rho_{2}\)
Answer & Solution
Correct Answer
(C) \(2 \times{ }^{20} \mathrm{C}_{2}\)
Step-by-step Solution
Detailed explanation
Required number of ways \(={}^{20} C_{2} \times 2!\) \(= {}^{20}P_{2}\)
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