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.
12 kms.
D.
12 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. 9000
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
15 minutes