Two people will take 2 hours to paint 2 rooms.How many people required to paint 18 rooms in 6 hours ?

Answer:

6 people is the answer..See How.,

2 people can paint 2 rooms in 2 hours..Similarly,
6 people can paint 6 rooms in same 2 hours.

so the same 6 people can paint 18(6*3)rooms in 6(2*3)hours.