A factory is operating in two shifts, day and night, with 70 and 30 workers respectively. If per day mean wage of the day shift workers is Rs 54 and per day mean wage of all the workers is Rs 60, then per day mean wage of the night shift workers (in Rs) is:

Total number of workers=70+30=100
Given per day mean wage of all the workers is Rs 60.
So, total daily wage of all workers = 100 * 60 = Rs 6000
Total daily wage of day shift workers = 70 * 54 = Rs 3780
Total daily wage of night shift workers = Total daily wage of all workers - Total daily wage of day shift workers
= 6000 - 3780 = Rs 2220
Number of night shift workers = 30
Per day mean wage of night shift workers = Total daily wage of night shift workers / Number of night shift workers
= 2220 / 30 = Rs 74