Arithmatical  Boat’s and Streams
DIRECTIONS : Problems based on Boats and Streams.
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 
Solution 
Speed Downstream  = (13 + 4) km/hr 
= 17 km/hr. 
Time taken to travel 68 km downstream  =(68 / 17)hrs 
= 4 hrs. 

2. 
The speed of a boat in still water is 15 km/hr and the rate of current is 3 km/hr. The distance travelled downstream in 12 minutes is 

A. 1.2 km 

B. 1.8 km 

C. 2.4 km 

D. 3.6 km 
Solution 
Speed Downstream  = (15 + 3) km/hr 
= 18 km/hr. 
Distance travelled  =(18 x 12/60)hrs 
= 3.6km. 

3. 
A boat takes 19 hours for travelling downstream from point A to point B and coming back to a point C midway between A and B. If the velocity of the stream is 4 kmph and the speed of the boat in still water is 14 kmph, what is the distance between A and B ? 

A. 160 km 

B. 180 km 

C. 200 km 

D. 220 km 
Solution 
Speed Downstream  = (14 + 4) km/hr 
= 18 km/hr. 
Speed upstream  =(14  4) km/hr 
= 10 km/hr.. 
Let the distance b/w A and B be xkm.Then 
=(x/18+ x/2 / 10) 
= 19 
= 19x / 180 = 19 
x= 180. 

4. 
A boat running downstream covers a distance of 16 km in 2 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water? 

A. 4 km/hr 

B. 6 km/hr 

C. 8 km/hr 

D. Data inadequate 
Solution 
Rate Downstream  = (16 / 2) kmph 
= 8 kmph 
Rate upstream  =(16 / 4) kmph 
= 4 kmph. 
Speed in still water  = 1 / 2 (8 + 4)kmph 
= 1/2 x 12 
= 6 kmph. 

5. 
A man can row upstream at 8 kmph and downstream at 13 kmph. The speed of the stream is 

A. 2.5 km/hr 

B. 4.2 km/hr 

C. 5 km/hr 

D. 10.5 km/hr 
Solution 
Speed of stream  = 1 / 2 (13  8 )kmph 
= 1/2 x 5 
=5 /2 
= 2.5 
