A boat travels upstream from A to B and back from B to A in 5 hours. The speed of the boat in still water is 8 km/hour and the speed of the current is 4 km/hour. Then, the distance from A to B is:

• 9 kms.

• 10 kms.

• 12 kms.

• 15 kms.

A ground 100×80 meter2 has two cross roads in its middle. The road parallel to the length is 5 meter wide and the other road is 4 meter wide, both roads are perpendicular to each other. The cost of laying the bricks at the rate of Rs. 10 per m2, on the roads, will be

• Rs. 7000

• Rs. 8000

• Rs. 9000

• Rs. 10000

Pipe A can fill a tank in 10 hours and pipe B can fill the same tank in 12 hours. Both the pipes are opened to fill the tank and after 3 hours pipe A is closed. Pipe B will fill the remaining part of the tank in

• 5 hours

• 4 hours

• 5 hours 24 minutes

• 3 hours

Taps ‘A’ and ‘B’ can fill a tank in 37 ½ minutes and 45 minutes respectively. Both taps are opened and after some time tap ‘B’ is turned off. The tank is filled completely in exactly 30 minutes, if tap ‘B’ is turned off after:

• 9 minutes

• 10 minutes

• 15 minutes

• 12 minutes