Permutation Combination Question 14
Question 14 - 30 January - Shift 2
The number of seven digits odd numbers, that can be formed using all the seven digits 1, 2, 2, 2, 3, 3, 5 is __________
Show Answer
Answer: 240
Solution:
Formula: Non-Consecutive Selection
Digits are 1, 2, 2, 2, 3, 3, 5
If unit digit 5 , then total numbers $=\frac{6 !}{3 ! 2 !}$
If unit digit 3 , then total numbers $=\frac{6 !}{3 !}$
If unit digit 1 , then total numbers $=\frac{6 !}{3 ! 2 !}$
$\therefore$ total numbers $=60+60+120=240$
