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Boats & Streams Solved Questions For IBPS, SBI and Other Bank Exams - Page 2

You will find 7 problems in 2 pages..

Boats & Streams Solved Questions (Page 2 of 2)

Question 1

A boat runs at 22 km per hour along the stream and 10 km per hour against the stream. Find the ratio of speed of the boat in still water to that of the speed of tht stream.

a) 2:3 b) 8:3 c) 5:3 d) 7:3

Answer : b) 8:3

Solution :

Speed along the stream = speed downstream = a = 22 km/hr
And speed against the stream = speed upstream = b = 10 km/hr.
Now, the speed in still water = a + b / 2 km/hr = (22 + 10) / 2 = 16 km/hr.
And the speed of stream = a - b / 2 km/hr = (22 - 10) / 2 = 6 km/hr.
Required ratio = speed in still water : speed of stream = 16:6 = 8:3.


Question 2

A boat takes 12 hours to cover 64 km downstream and 8 hours to cover 32 km upstream. Then the speed of the boat in still water is:

a) 14/3 km/hr b) 3/2 km/hr c) 6/5 km/hr d) 8/7 km/hr

Answer : a) 14/3 km/hr

Solution :

Distance covered in downstream = 64 km
Time taken in downstream = 12 hours.
Rate of downstream = distance / time = a = 64 km / 12 hours = 16 / 3 km/hr.

Distance covered in upstream = 32km
Time taken in upstream = 8 hours.
Rate of upstream = distance / time = b = 32km / 8 hours = 4 km/hr.
Speed in still water = (a + b) / 2 = (1/2)(16/3 + 4) km/hr = (1/2)(28/3) = 14/3 km/hr.


Question 3

Find the rate of the stream, if a boat covers 120 km downstream and 40 km upstream in 4 hours.

a) 15 km/hr b) 20 km/hr c) 10 km/hr d) 25 km/hr

Answer : c) 10km/hr.

Solution :

Distance covered in downstream = 120 km
Time taken in downstream = 4 hours.
Rate of downstream = distance / time = a = 120km / 4 hours = 30 km/hr.

Distance covered in upstream = 40 km
Since it takes same time to cover this 40km,
Time taken in upstream = 4 hours.
Rate of upstream = distance / time = b = 40km / 4 hours = 10 km/hr.
Speed of stream = (a - b)/2 = (1/2)(30 - 10) km/hr = 10 km/hr.


Question 4

If a man rows 4 km downstream in 3 hours and 2 km upstream in 2 hours then how long will he take to cover 8 km in stationary (still) water?

a) 5 hours b) 9 hours c)8 hours d) none of these

Answer : d) none of these.

Solution :

Distance covered in downstream = 4 km
Time taken in downstream = 3 hours.
Rate of downstream = distance / time = a = 4km / 3 hours = 4/3 km/hr.

Distance covered in upstream = 2 km
Time taken in upstream = 2 hours.
Rate of upstream = distance / time = b = 2 km / 2 hours = 1 km/hr.

Speed in still water = (a + b)/2 = (1/2)(4/3 + 1) km/hr = (1/2)(4 + 3)/3 = 7/6 km/hr.
Time Taken to cover 8 km in still water = distance / speed = 8 x 6/7 = 48 / 7 = 7 hours (approximately).
Hence the answer is option d.


Boats & Streams Solved Questions (Page 2 of 2)

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