B.4 hours

C.8 hours

D.6 hours

E.None of these

2) If the ratio of the speed of boat to stream is 5:2 and the boat to covers 525 km downstream and upstream in 50 hours, then find the speed of the boat along with stream?

A.28 kmph

B.35 kmph

C.42 kmph

D.21 kmph

E.None of these

3) The ratio of the speed of boat in upstream and the speed of current is 2:1. If the speed of boat in still water is 24 kmph, then find the speed of upstream?

A.12 kmph

B.16 kmph

C.20 kmph

D.15 kmph

E.18 kmph

4) The speed of boat A is 50% more than the speed of boat B. If boat A covers 140 km upstream in 14 hours and the speed of stream is 5 kmph, then find the time taken by boat B covers 120 km downstream and 45 km upstream?

A.13 hours

B.15 hours

C.17 hours

D.19 hours

E.20 hours

5) The speed of the boat in still water is x kmph and the speed of upstream is x/2 kmph. If the boat covers 216 km downstream and 108 km upstream in 20 hours, then find the time taken by the boat covers 162 km upstream and downstream?

A.18 hours

B.20 hours

C.22 hours

D.24 hours

E.27 hours

Answers :

1) Answer: A

Let the speed of the boat=5x

And the speed of the stream=1x

Downstream speed of the boat=36*60/30=72 kmph

Upstream speed of the boat=72*4x/6x=48 kmph

Required time=240/48=5 hours

2) Answer: B

525/(5x + 2x) + 525/(5x – 2x) = 50

75 + 175 = 50x

x = 5

Speed of downstream = 7 * 5 = 35 kmph

3) Answer: B

Speed of boat = 24 kmph

24 – x = 2x

3x = 24

x = 8

Speed of upstream = 2 * 8 = 16 kmph

4) Answer: C

Upstream Speed of boat A = 140/14 = 10 kmph

Speed of boat A = 10 + 5 = 15 kmph

Speed of boat B = 15 * 100/150 = 10 kmph

Required time = 120/(10 + 5) + 45/(10 – 5)

= 17 hours

5) Answer: D

Speed of stream = x – x/2 = x/2

216/(x + x/2) + 108/(x/2) = 20

432/3x + 216/x = 20

360 = 20x

x = 18

Speed of stream = 18/2 = 9 kmph

Speed of downstream = 9 + 18 = 27 kmph

Required time = 162/27 + 162/9

= 24 hours