JEE Mains · Maths · STD 11 - 6. permutation and combination
Five digit numbers are formed using the digits \(1,2 , 3,5,7\) with repetitions and are written in descending order with serial numbers. For example, the number \(77777\) has serial number \(1\). Then the serial number of \(35337\) is \(.........\).
- A \(718\)
- B \(156\)
- C \(1436\)
- D \(1472\)
Answer & Solution
Correct Answer
(C) \(1436\)
Step-by-step Solution
Detailed explanation
No of \(5\) digit numbers starting with digit 1 \(=5 \times 5 \times 5 \times 5=625\) No of \(5\) digit numbers starting with digit 2 \(=5 \times 5 \times 5 \times 5=625\) No of \(5\) digit numbers starting with \(31\) \(=5 \times 5 \times 5=125\) No of \(5\) digit numbers…
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