21). A motorboat can travel at 10 km/h in still water. It travelled 91km downstream in a river and then returned to the same place, taking altogether 20 h. The rate of flow of river is
A). 3 km/h |
B). 4 km/h |
C). 2 km/h |
D). 5 km/h |
|
22). A man can row against the current three-fourth of a kilometre in 15 min and returns same distance in 10 min, then ratio of his speed to that of current is
A). 3 : 5 |
B). 5 : 3 |
C). 1 : 5 |
D). 5 : 1 |
|
23). The speed of the current is 5 km/h. A motorboat goes 10 km upstream and back again to the starting point in 50 min. The speed, (in km/h) of the motorboat in still water is
A). 20 km/h |
B). 26 km/h |
C). 25 km/h |
D). 28 km/h |
|
24). A man can row 6 km/h in still water. If the speed of the current is 2 km/h, it takes 3 h more in upstream than in the downstream for the same distance. The distance is
A). 30 km |
B). 24 km |
C). 20 km |
D). 32km |
|
25). A boat goes 48 km downstream in 20 h. It takes 4 h more to cover the same distance against the stream. What is the speed of the boat in still water?
A). 2.2 km/h |
B). 2 km/h |
C). 4 km/h |
D). 4.2 km/h |
|
26). Pawan can row 24 km/h in still water. When the river is running at 4.8 km/h, it takes him 1 h to row to a place and to come back. How far is the place?
A). 11.52 km |
B). 14 km |
C). 12.52 km |
D). 15 km |
|
27). Sameer can row a certain distance downstream in 24 h and can come back covering the same distance in 36 h. If the stream flows at the rate of 12 km/h, find the speed of Sameer in still water.
A). 30 km/h |
B). 15 km/h |
C). 40 km/h |
D). 60 km/h |
|
28). A sailor sails a distance of 48 km along the flow of a river in 8 h. If It takes 12 h to return the same distance, then the speed of the flow of the river is
A). 0.5 km/h |
B). 1 km/h |
C). 1.5 km/h |
D). 2 km/h |
|
29). Speed of motorboat in still water is 45 km/h. If the motorboat travels 80 km along the stream in 1 h 20 min, then the time taken by it to cover the same distance against the stream will be
A). 4 h 20 min |
B). 3 h 40 min |
C). 2 h 40 min |
D). 2 h 55 min |
|
30). A boat has to travel upstream 20 km distance from point X of a river to point Y. The total time taken by boat in travelling from point X to Y and Y to X is 41 min 40 s. What is the speed of the boat?
A). 66 km/h |
B). 72 km/h |
C). 48 km/h |
D). Cannot be determined |
|