Boats & Streams

1

At his usual  rowing rate , Rahul can  travel 12 miles downstream in a certain river in 6 hours less than it take him o travel the same distance upstream. But if he could double his usual rowing rate for his 24 mile round trip , the downstream  12 miles would then take only  one hour less han  he upstream 12 miles. what is he speed of the current in miles  per hour ?

A. 1 1/3
B. 1 2/3
C. 2 1/3
D. 2 2/3

2

A boat covers 24 km upstream and 36 km downstream in 6 hours while it covers 36 km upstream and 24 km downstream in 6 1/2 hours. The velocity of the current is  :

A. 1 km/hr
B. 1.5 km/hr
C. 2 km/hr
D. 2.5 km/hr

3

A man rows to a place 48 km distant and back  in 14 hours. He finds that he can row 4 km with the stream  in the same time as 3 km against the stream . The rate of one stream is :

A. 1 km/hr
B. 1.5 km/hr
C. 1.8 km/hr
D. 3.5 km/hr

4

A boat takes 90 minutes less to travel 36 miles downstream than to travel the same distance upstream . If the speed of the boat in still water is 10 mph, the speed of the stream is :

A. 2 mph
B. 2.5 mph
C. 3 mph
D. 4 mph

5

The speed of a boat in still water is 10 km/hr . If i can ravel  26 km downstream and  14 km upstream in the same time , the speed of he stream is :

A. 2 km/hr
B. 2.5 km/hr
C. 3 km/hr
D. 4 km/hr