Trains Boats and Streams Practice Test 2 with solutions

Question : 34 of 40

Marks: +1, -0

A boat goes 30 km upstream and 44 km downstream in 10 hours. In 13 hours, it can go in the 40 km upstream and 55 km downstream. The speed of the boat in the still water.

3 km/hour
8 km/hour
4 km/hour
5 km/hour
None of these

Validate

Solution:

Suppose 30 km upstream is covered in 3x hours and 40 km upstream in 4x hours, 44 km downstream is covered in 4y hours and 55 km downstream is covered in 5y hour then,
3x + 4y = 10 ......(i)
4x + 5y = 13 ......(ii)
Solving (i) and (ii) we get x = 2 and y = 1
So, upstream speed =

{30}/{3x}

= 5 km/hour
Downstream speed =

{44}/{4(y)}

= 11 km/hour
So, speed of the boat in the still water
=

{11+5}/2

= 8 km/hour

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