Directions (47-48) : Study the following graph carefully to answer the given questions : Time taken by the pipes to fill a tank/cistern (hours/minutes)

47. A large cistern can be filled by two pipes A and B. How many minutes will it take to fill the cistern from an empty state, if B is used for half the time and A and B fill it together for the other half ?

1. 7·5 minutes

2. 2·5 minutes

3. 4·0 minutes

4. 8·0 minutes

Correct Answer :

8·0 minutes