NCHMCT JEE 2015 Question Paper with solutions for online practice

Let, speed of boat = x km/hr and speed of stream = y km/hr
According to the question,

d

y+x

= 2
⇒ 2x + 2y = d ...(i)
and

d

x−y

= 5
⇒ 5x – 5y = d ...(ii)
2x + 2y = d ] × 5
5x – 5y = d ] × 2
10x + 10y = 5d
10x – 10y = 2d
––––––––––––
20x = 7d
⇒ x =

7d

20

2(

7d

20

) + 2y = d
⇒ 2y = d -

7d

10

=

3d

10

⇒ y =

3d

20

Required ratio =

7d 20

3d 20

= 7 : 3