100+ Boats and Streams Questions for IBPS, SBI PO, SO, Clerk - 1

Question: 1

Twice the speed downstream is equal to the thrice the speed upstream, the ratio of speed in still water to the speed of the current is

(A) 1:3

(B) 1:5

(C) 2:3

(D) 5:1

Ans: D

Let, speed in still water = x km/h.

Speed of current = y km/h.

Speed downstream = (x + y) km/h.

Speed upstream = (x – y) km/h.

∴ 2(x + y) = 3(x – y)

∴ x = 5y

or, $${x}/{y}$$ = $${5}/{1}$$ or 5 : 1.

Question: 2

The speed of a boat in still water is 8 Km/h. If its speed downstream be 15 Km/h, then speed of the stream is

(A) 7 Km/h

(B) 7.5 Km/h

(C) 9 Km/h

(D) 9.5 Km/h

Ans: A

Speed of the boat downstream = 15 Km/h.

Speed of the boat in still water = 8 Km/h.

Let the speed of the stream = y Km/h.

We have, 15 = 8 + y

∴ y = 15 – 8 = 7 Km/h.

Question: 3

A boat takes 8 hours to cover a distance while travelling upstream, whereas while travelling downstream it takes 6 hours. If the speed of the current is 4 kmph, what is the speed of the boat in still water?

(A) 12 kmph

(B) 16 kmph

(C) 24 kmph

(D) 28 kmph

Ans: D

Let the speed of the boat in still water be x kmph.

Then, speed downstream = (x + 4) kmph,

Speed upstream = (x - 4) kmph.

∴ (x + 4) × 6 = (x - 4) × 8

⇒ 6x + 24 = 8x - 32 ⇒ 2x = 56 ⇒ x = 28 kmph.

Question: 4

The speed of a boat when travelling downstream is 32 km/hr, whereas when travelling upstream it is 28 km/hr, what is the speed of the boat in still water and at the speed of the stream?

(A) 2 km/hr

(B) 3 km/hr

(C) 4 km/hr

(D) 5 km/hr

Ans: A

Speed of boat in still water =$${1}/{2}(32 + 28)$$ km/hr = 30 km/hr.

Speed of stream = $${1}/{2}(32 - 28)$$ km/hr = 2 km/hr.

Question: 5

If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 3 kmph, then the speed of the boat in still water is

(A) 4 .2 km / hr

(B) 9 km / hr

(C) 11 km / hr

(D) 13 km /hr

Ans: D

Rate upstream = $$({7} / {42} × 60)$$ kmph = 10 kmph.

Speed of stream = 3 kmph.

Let speed in still water be x km/hr.

Then, speed upstream = (x - 3) km/hr.

∴ x - 3 = 10 or x = 13 km/hr.

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