1. 

A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream.

A. 2 hours
B. 3 hours
C. 4 hours
D. 5 hours

2. 

A boat running upstream takes 8 hours 48 minutes to cover a certain distance, while it takes 4 hours to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the water current respectively?

A. 2 : 1
B. 3 : 2
C. 8 : 3
D. Cannot be determined

3. 

A motorboat, whose speed in 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. The speed of the stream (in km/hr) is:

A. 4
B. 5
C. 6
D. 10

4. 

In one hour, a boat goes 11 km/hr along the stream and 5 km/hr against the stream. The speed of the boat in still water (in km/hr) is:

A. 3 km/hr
B. 5 km/hr
C. 8 km/hr
D. 9 km/hr

5. 

A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is:

A. 8.5 km/hr
B. 9 km/hr
C. 10 km/hr
D. 12.5 km/hr