Aptitude

1

Find the speed of the boat in still water, if a boat covers a certain distance upstream in 2 hours, while it comes back in 11/2 hours. If the speed of the stream be 3 kmph.

a

12 Kmph

b

18 Kmph

c

21 Kmph

d

24 Kmph

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

Speed downstream = (x + 3) kmph,

Speed upstream = (x - 3)kmph.

(x - 3) * 2 = (x + 3) * 3/2

4x - 12 = 3x + 9

x = 21kmph.

2

Mayur takes thrice as long to row a distance against the stream as to row the same distance in favor of the stream. The ratio of the speed of the boat(in still water) and the stream is:

a

3:1

b

1:3

c

2:1

d

1:1

Let speed in still water be x and speed of stream be y

(Speed in still water) : (Speed of stream)=x:y

Distance is same, then time taken downstream is t, and time taken to travel upstream is 3t.

d=d

[(x+y) / t] = [(x-y) / (3t)]

x+y= 3x-3y

2x = 4y

x/y = 4/2 = 2/1

x:y = 2:1