A seven digit number is formed using digits 3, 3, 4, 4, 4, 5, 5.

Question

A seven digit number is formed using digits 3, 3, 4, 4, 4, 5, 5. The probability, that number so formed is divisible by 2, is :

Accepted Answer

Digits = 3, 3, 4, 4, 4, 5, 5

Total 7 digit numbers = $${{7!} \over {2!2!3!}}$$

Number of 7 digit number divisible by 2 $$ \Rightarrow $$ last digit = 4

Now 7 digit numbers which are divisible by 2 = $${{6!} \over {2!2!2!}}$$

Required probability = $${{{{6!} \over {2!2!2!}}} \over {{{7!} \over {3!2!2!}}}} = {3 \over 7}$$

Solutions · 1