1. Speed of a man in still water is 5 km/hr and the river is running at

3km/hr. The total time taken to go to a place and come back is 10

hours. What is the distance travelled?

A.10 km

B.16 km

C.24 km

D.32 km

E.36 km

Answer & Explanation

Answer – D.32 km

Explanation :

Down speed= 5+3= 8

Up speed= 5-3=2

Let distance travelled = X

(X/8)+(X/2)= 10

X= 16 km

Total distance is 16+16=32

2. A boat running upstream takes 9 hours 48 minutes to cover a

certain distance, while it takes 7 hours to cover the same distance

running downstream. What is the ratio between the speed of the

boat and speed of the water current respectively?

A.5:2

B.7:4

C.6:1

D.8:3

E.2:5

Answer & Explanation

Answer – C.6:1

Explanation :

Distance covered upstream in 9hrs 48 min = Distance covered downstream in

7hrs

(X-Y) 49/5=(X+Y)7

X/y=1/6

3. A man can row 8 km/hr in still water. When the river is

running at 4 km/hr, it takes him 2 1/3hr to row to a place

and come back. How far is the place?

A.4 km

B.5 km

C.7 km

D.10 km

E.None of these

Answer & Explanation

Answer – C.7 km

Explanation :

Downstream speed = 8+4= 12 => a

Upstream speed = 8-4= 4 => b

Distance = a*b/(a+b) * total time (t)

= 12*4/16 * 7/3

= 7kms

4. A boat goes 4 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 15 km in stationary water?

A.2 hour 15 min

B.2 hour

C.3hr

D.3hr 30 min

E.None of these

Answer & Explanation

Answer – C.3hr

Explanation :

Rate downstream = 1/10 * 60 = 6kmph

Rate upstream = 4 km/hr.

Speed in still water = ½ * 10 = 5 kmph

Required time = 15/5 = 3 hr

If you have doubts on logical reasoning or critical reasoning, ask here.

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