# Boats and Streams

1. The difference between the downstream and upstream speeds of a boat is 12 km/hr. If the speed of the boat in still water is 14 km/hr more than of the current, then find the downstream speed of the boat is....

A) 19 km/hr      B) 32 km/hr      C) 26 km/hr      D) 28 km/hr      E) None of these

Sol: Let boat speed = x

Stream Speed = y

Downstream speed = x + y

Upstream speed = x − y

(x + y) − (x − y) = 12 km/hr

x + y − x + y = 12 2y = 12

y= 6 km/hr

speed of the boat (x) = 6 + 14 = 20 km/hr

then downstream speed of the boat

= x + y = 20 + 6 = 26 km/hr

Ans: 26 km/hr

2. The speed of the boat in still water is 80% more than the speed of the stream. if the boat takes 5 hours to cover 280 km in downstream, then find the speed of the stream.

A) 15 km/hr      B) 22.5 km/hr    C) 20 km/hr    D) 25 km/hr     E) None of these

Sol: Speed of the boat (x) = 180% of speed of the stream (y)

speed of stream (y) = 20 km/hr

Ans: C

3. A boat can cover 54 km in still water in 6 hours and it can cover 210 km upstream and same distance in downstream in total of 48 hours. The boat can cover 72 km upstream in how much more time than the time taken to cover 63 km downstream?

A) 4.8 hours     B) 3.6 hours    C) 2.5 hours    D) 3 hours     E) None of these

Ans: 3.6 hours

4. The ratio of the downstream to upstream speed of the boat is 5 : 3 and the time taken by the boat to cover 288 km in still water is 18 hours. Find the sum taken by the boat to cover 400 km in downstream and 240 km in still water?

A) 30 hours    B) 20 hours    C) 28 hours    D) 35 hours     E) None of these

= 35 hour

Ans: None of these

5. A boat takes 249 min to cover 116.2 km in upstream. If the boat travelled in upstream for 2.5 hours and in downstream for 3 hours then it covered a total of 178 km. What is the speed of the boat in still water?

A) 32 km/hr     B) 40 km/hr    C) 30 km/hr     D) 28 km/hr     E) 35 km/hr

Ans: 32 km/hr

6. The ratio of upstream to downstream speed of a boat is 9 : 11 respectively and the boat takes 45 minutes more to cover 135 km upstream than it takes to cover 132 km downstream. Find the speed of the boat in still water?

A) 40 km/hr     B) 32 km/hr     C) 50 km/hr     D) 45 km/hr      E) 36 km/hr

Sol: upstream speed : downstream speed

x = 4

upstream speed = 9x = 9 × 4 = 36

downstream speed = 11x = 11 × 4 = 44

Ans: 40 km/hr

7. A man can swim 24 km in 4 hours in still water. He swims 35 km downstream in 5 hours. What is the time taken by the man to swim 52.5 km upstream?

A) 7 hours    B) 8 hours      C) 9 hours      D) 10 hours 30 min     E) 11 hours 40 minutes

x + y = 7

6 + y = 7

stream speed (y) = 1 km/hr

Ans:  11 hours 40 minutes

8. In 4 hours, a boat can travel 8 km more in downstream as compared to that in upstream. Find the total time taken by the boat to travel 126 km upstream and 160 downstream. If the time taken by the boat to travel 95 km in still water is 5 hours.

A) 8 hours    B) 10 hours      C) 18 hours      D) 20 hours     E) 15 hours

(19 + y) × 4 − (19 − y) × 4 = 8

y = 1 km/hr

Ans: 15 hours

9. The sum of the speed of the boat downstream and the speed of the boat upstream is approximately 34.98 km/hr. Boat travels upstream for 170 mins and downstream for 241 mins. What is the approximate total distance travelled by the boat upstream and the distance travelled by the boat downstream, if speed of stream is 4.02 km/hr? (in km)

A) 112      B) 130      C) 160      D) 125      E) 118

Sol: x + y + x − y = 32

2x = 35

x = 17.5 km/hr

y = 4 km/hr

total distance

= 125

Ans: 125

10. A sailor travelling from point A to B, dropped his hat at point A. The sailor, who was travelling downstream at 36 km/hr reached point B in 2 hours and the hat reached point B in 8 hours. Find the speed of the boat in still water.

A) 9 km/hr     B) 24 km/hr     C) 27 km/hr     D) 30 km/hr     E) None of these

Sol: Distance = 36 × 2 = 72 km

Speed of the boat = 36 − 9

= 27 km/hr

Ans: 27 km/hr

11. A boat can row to a place 320 km away and come back in 24 hours. The time to row 60 km with the stream is same as the time to row 48 km against the stream. Find the speed of current?

A) 3 km/hr      B) 4.5 km/hr     C) 6 km/hr     D) 12 km/hr     E) 1.25 km/hr

Ans:  3 km/hr

12. The ratio of the distance covered by the boat in downstream in 6 hours to the distance covered by the boat in still water in 5 hours is 3 : 2. If the upstream speed of the boat is 18 km/hr, then find the speed of the boat in still water.

A) 30     B) 27     C) 21      D) 24     E) 36

upstream speed x − y = 18

3 parts →18

1 part → 6

boat speed (x) = 4 parts = 4 × 6 = 24 km/hr

Ans: 24

13. The speed of the boat upstream is 6 km/hr less than that downstream. If the speed of the boat in still water is 21 km/hr, what is the time taken by the boat to travel 108 km upstream and the same distance downstream together?

A) 11 hrs 30 min     B) 12 hrs     C) 12 hrs 30 min     D) 11 hrs     E) 10 hrs 30 min

Sol: (x + y) − (x − y) = 6

x + y − x + y = 6 ⇒ 2y = 6

y = 3 km/hr

boat speed (x) = 21 km/hr

Ans:  10 hrs 30 min

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14. If a boat takes 4 hours to travel 108 km downstream and it takes 5 hours to travel 115 km upstream. Find the time taken by boat to cover 621 km both upstream and downstream?

A) 30     B) 40     C) 60     D) 50    E) 100

Ans: 50

Posted Date : 28-04-2023

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