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1. Time and Distances - 4
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2. 1. Races and Games
2. Problems on Trains
3. Boats and Streams
Time and Distances
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3. Boats and Streams
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4. UPSTREAM: travelling opposite to the flow of stream
DOWNSTREAM: travelling same to the flow of stream
If the speed of boat in still water is ‘x’ km/hr and speed of the
stream is ‘y’ km/hr, then
Speed of boat upstream = x - y km/hr
Speed of boat downstream = x + y km/hr
Basics:
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5. 1. Time taken by a boat to travel upstream is 3 times the time taken in
downstream. If the speed of stream is 3km/hr, then find the speed of
boat in still water?
2. Total time taken by a boat to travel 45km upstream and the same
distance downstream is 14hrs. If the speed of boat in still water is
7km/hr, then find the speed of stream?
3. A boat can travel 30km upstream and 44km downstream in 10hrs. It
can also travel 40km upstream and 55km downstream in 13hrs. Find
the speed of boat in still water?
4. A man can row upstream at a speed of 20km/hr and downstream at a
speed of 27km/hr. find the speed of the stream?
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6. The speed of boat upstream is 35km/hr and the speed of the
stream is 1.5km/hr. what is the distance travelled by the boat
downstream in 4hrs?
5.
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7. Time taken by a boat to travel upstream is 3 times the time taken in
downstream. If the speed of stream is 3km/hr, then find the speed of boat
in still water?
Ans :
NOTE:
If distance is constant, then speed and time are
inversely proportional to each other.
 3( x - y ) = x + y
 X = 6 kmph
1.
speed of boat in still water = 6 kmph
Units must be either
in km/hr or m/sec
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8. Total time taken by a boat to travel 45km upstream and the same
distance downstream is 14hrs. If the speed of boat in still water is
7km/hr, then find the speed of stream?
2.
Speed of stream = 2kmph.
Ans :
From the question x = 7
Total time taken in upstream + downstream = 14hrs
 = total time taken

 y = 2 kmph
Units must be either
in km/hr or m/sec
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9. A boat can travel 30km upstream and 44km downstream in 10hrs. It
can also travel 40km upstream and 55km downstream in 13hrs. Find
the speed of boat in still water?
3.
Units must be either
in km/hr or m/sec
speed of boat in still water = 8km/hr
Ans :
From the question
Total time taken in upstream + downstream = 10hrs


 x = 8 km/hr
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10. A man can row upstream at a speed of 20km/hr and downstream at a
speed of 27km/hr. find the speed of the stream?
4.
speed of the stream = 3.5km/hr
Ans :
From the question
x – y = 20 and x + y = 27
 y = 3.5 km/hr
Units must be either
in km/hr or m/sec
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11. The speed of boat upstream is 35km/hr and the speed of the stream is
1.5km/hr. what is the distance travelled by the boat downstream in
4hrs?
5.
Distance travelled by the boat downstream in 4hrs = 142km
Ans :
From the question
x – y = 35 and y = 1.5 km/hr
 x = 36.5 km/hr
 x + y = 38 km/hr
 Distance travelled by boat = 38km/hr 4 = 142 km
Units must be either
in km/hr or m/sec
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12. Subscribe to :
Problems for practice are given in the description of the video.
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13. Practice problems
on Boats and Streams
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14. • The speed of boat in still water is 10 km/hr and the speed of the stream
is 2 km/hr. what is the time taken by the boat to travel 24km upstream?
• A boat can travel 16km upstream and 24km downstream in 4hrs. It can
also travel 24km upstream and 18km downstream in 4.5hrs. Find the
speed of boat in still water?
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15. The speed of boat in still water is 10 km/hr and the speed of the
stream is 2 km/hr. what is the time taken by the boat to travel 24km
upstream?
1.
Ans :
x = 10 km/hr
y = 2 km/hr
Speed of the boat in upstream = 8 km/hr
Time taken = 24/8 = 3hrs
Time taken by the boat to travel 24km upstream = 3 hrs
Units must be either
in km/hr or m/sec
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16. A boat can travel 16km upstream and 24km downstream in 4hrs. It can
also travel 24km upstream and 18km downstream in 4.5hrs. Find the
speed of boat in still water?
2.
Speed of boat in still water = 2.5km/hr
Ans :
From the question
Total time taken in upstream + downstream = 4hrs


 x = 2.5 km/hr
Units must be either
in km/hr or m/sec
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17. Subscribe to :
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