Three small pumps and a large pump are filling a tank. Each of the three small pump works at 2/3 the rate of the large pump. If all four pumps work at the same time, they should fill the tank in what fraction of the time that it would have taken the large pump alone?

- 2/3
- 1/3
- 4/7
- 3/4

**Answer**

Since, each of the three small pump works at 2/3 the rate of the large pump.

Work by three small pumps = Work by two large pumps

All 4 pumps = Three small pumps + One large pump = Three large pumps

All 4 pumps / 1 large pump = 1/3

**The correct option is B.**