Question:

All possible number are formed using the digits 1, 1, 2, 2, 2, 2, 3, 4, 4 taken all at a time. The number of such numbers in which the odd digits occupy even places is:

160

180

175

162

Correct option is D. 180
Number of such numbers = 4C3 × 3! / 2! × 6! / (2!4!) = 180