100+ Boats and Streams Questions and Answers for SSC Exams - 1

Question: 1

A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?

(A) 40 minutes

(B) 1 hour

(C) 1 hr 05 min

(D) 1 hr 15 min

Ans: D

Rate downstream = $$({1}/{10} × 60)$$ km/hr = 6 km/hr.

Rate upstream = 2 km/hr.

Speed in still water = $${1}/{2}(6 + 2) $$km/hr = 4 km/hr.

∴ Required time = $${5}/{4}$$ hrs = $$1{1}/{4}$$ = 1 hr 15 min.

Question: 2

If a man rows at the rate of 5 kmph in still water and his rate against the current is 3.5 kmph, then the man’s rate along the current is

(A) 4.25 kmph

(B) 4.75 kmph

(C) 6 kmph

(D) 6.5 kmph

Ans: D

Let the rate along the current be x kmph.

Then, $${1}/{2}(x + 3.5) - 5$$ or x = 6.5 kmph.

Question: 3

A swimmer covers a distance of 28 Km against the current and 40 Km in the direction of the current. If in each case he takes 4 hours, then the speed of the current is

(A) 1.5 Km/h

(B) 2.5 Km/h

(C) 3.5 Km/h

(D) 4.5 Km/h

Ans: A

Speed of the swimmer upstream = $${28}/{4}$$ = 7 Km/h.

Speed of the swimmer downstream = $${40}/{4}$$ = 10 Km/h.

∴ Speed of the stream

= $${1}/{2} (Downstream Speed - Upstream speed)$$ = $${1}/{2} (10 -7)$$ = $${3}/{5}$$ =1.5 Km/h.

Question: 4

A man can row 6 Km/h in still water. If the river is running at 2 Km/h, it takes 3 hours more in upstream than to go downstream for the same distance. How far is the place?

(A) 22 Km

(B) 24 Km

(C) 28 Km

(D) 32 Km

Ans: B

The required distance

= $$({x^2 – y^2)t} / {2y}$$ = $${(36 - 4)^3} / {2 × 2}$$ = 24 km.

Question: 5

A man can row three quarters of a kilometer against the stream in $$11{1}/{4}$$ minutes. The speed (in km/hr) of the man in still water is

(A) 2

(B) 3

(C) 4

(D) 5

Ans: D

Rate upstream = $$({750} / {675})$$ m/sec = $${10}/{9}$$ m/sec.

Rate downstream = $${750}/{450}$$ m/sec = $${5}/{3}$$ m/sec.

∴ Rate in still water = $${1}/{2} ({10} /{9} + {5}/{3})$$ m/sec

= $${25}/{18}$$ m/sec = $$({25} / {18} × {18}/{5})$$ km/hr = 5 km/hr.

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