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Boats & Streams Solved Questions For IBPS, SBI and Other Bank Exams - Page 1

You will find 7 problems in 2 pages..

Boats & Streams Solved Questions (Page 1 of 2)

Dear Reader,

Below you will find important formulas of boats & streams problems. Following that you will find solved questions. These questions will help you in preparation for all bank exams including IBPS, SBI, RRB and other banks.

Basic Formulas:

If the speed of a boat in still water is u km/hr and the speed of the stream or current is v km/hr, then:

   Speed downstream = (u + v) km/hr.

   Speed upstream = (u - v) km/hr.

If the speed downstream is a km/hr and the speed upstream is b km/hr, then

   Boat speed in still water = ½ (a+b) km/hr.

   Rate of stream = ½ (a-b) km/hr.

Question1

If the speed of the stream is 2 km per hour, a boat can travel with a speed of 10 km per hour in still water and downstream in 60 km then the time taken by the boat to travel is:
a)2 hours b)4 hours c)5 hours d)3 hours

Answer : c) 5 hours.

Solution:

Note that "If the speed of a boat in still water is u km/hr and the speed of the stream is v km/hr, then:

Speed downstream = (u + v) km/hr and Speed upstream = (u - v) km/hr".

Now, here the speed of the downstream is ( 10 + 2 ) km/hr = 12 km/hr.

Then, the time taken to travel 60 km downstream = ( 60/12 ) hours = 5 hours.

Hence the answer is 5 hrs.


Question2

Find the speed of the stream when a boat takes 7 hours to travel 40km downstream at a rate of 12km per hour in still water.
a) 6.92km.hr b) 7.72km/hr c) 5.82km/hr d) 4.11km/hr

Answer: a) 6.92km/hr

Solution:

Let the speed of the stream be x km/hr. Then,

Downstream Speed = (12 + x) km/hr,

Upstream Speed = (12 - x) km/hr.

The boat covers, 40 km downstream in 7 hours then we have

[ 40 / (12 + x) ] + [ 40 / (12 - x) ] = 7

[40(12 - x) + 40(12 + x)] = 7(144 - x2)

960 = 1008 - x2

x2 = 48

x = 6.92

Hence the answer is 6.92 km/hr.


Question3

A boat covers a certain distance in half an hour downstream with the speed of 20km/hr in still water and the speed of current is 4km/hr. Then the distance travelled by the boat is:
a) 6km b) 7km c) 12km d) 4km

Answer: c) 12km

Solution:

Given that the speed of a boat in still water is 20 km/hr and speed of the stream is 4 km/hr.
Then the speed downstream = (20 + 4) km/hr = 24 km/hr.
The distance travelled in half an hour = 24 x 1/2 = 12 km.
Hence the distance travelled by the boat is 12 km.


Boats & Streams Solved Questions (Page 1 of 2)

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