A certain hotel has 1,400 single rooms and 420 double rooms. Each room is cleaned by one person. If one person can clean a single room every 15 mins and a double room every 20 minutes, how many cleaning persons are needed to clean all of the rooms if each person works for exactly 7 hours?
Is it 70?
total number of Hours required to clean all the rooms=
1400 * 15/60 + 420 * 20/60
If one person only spends 7 hrs then 70 people will be required, provided they do not go to lunch in between or go for a bio break.