Question

a boat covers a certain distance downstream in 4 hours and it covers the same distance up stream in 5 hours . if the speed of water is 2 km/hr. find the speed of boat in still water​

Answer 1

Answer:

1:5

explanation

Solution:Let distance be d km.Let speed of boat and stream be x km/hr and y km/hr.⇒ Upstream speed = (x – y)⇒ Downstream speed = (x + y)According to the questiond/(x – y) = 6⇒ d = (x – y)6     ...i)d/(x + y) = 4⇒ d = (x + y) 4     ...ii)From equation (i) and equation (ii)6(x – y) = 4(x + y)⇒ 6x – 6y = 4x + 4y⇒ 6x – 4x = 6y + 4y⇒ 2x = 10 y⇒ x : y = 5 : 1∴ Speed ratio of stream to boat = 1 : 5

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Answer 2

Answer:

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Quantitative Aptitude ≫ Speed Time and Distance ≫ Boat and River

Question:

A boat covers a certain distance downstream in 4 hours, but takes 6 hours to return to the starting point. What is the ratio of speed of stream to the speed of the boat in still water?

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Options:

5 : 1

4 : 3

1 : 4

1 : 5

Correct Answer: Option 4 (Solution Below)

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Solution:

Let distance be d km.

Let speed of boat and stream be x km/hr and y km/hr.

⇒ Upstream speed = (x – y)

⇒ Downstream speed = (x + y)

According to the question

d/(x – y) = 6

⇒ d = (x – y)6 ...i)

d/(x + y) = 4

⇒ d = (x + y) 4 ...ii)

From equation (i) and equation (ii)

6(x – y) = 4(x + y)

⇒ 6x – 6y = 4x + 4y

⇒ 6x – 4x = 6y + 4y

⇒ 2x = 10 y

⇒ x : y = 5 : 1

∴ Speed ratio of stream to boat = 1 : 5

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