question_answer

If the number of five digit numbers with distinct digits and 2 at the 10th place is 336 k, then k is equal to [JEE MAIN Held on 09-01-2020 Morning]

A) 8         

B)        6

C) 7                     

D) 4

Correct Answer: A

Solution :

[a]  There are eight options on first place (except the digits 0 and 2) and only one option at fourth place (digit '2'). Remaining three places can be occupied by any three digits out of 1, 3, 4, 5, 6, 7, 8 and 9. Number of such numbers \[=8\times 8\times 7\times 6=336\text{ }k\] \[\Rightarrow \,\,\,\,\,\,\,\,k=8\]