Question

I
ALS DU1CD
Pratik takes 8 hours to travel 36 km downstream and return
same spot. The speed of boat in still water is 12 km/hr. Find the
speed of the water current.​

Answer 1

Answer:

6 km/hr

Step-by-step explanation:

Luk @ the pic....

Answer 2

❏ Question:-

@ Pratik takes 8 hours to travel 36 km downstream and return same spot. The speed of boat in still water is 12 km/hr. Find the

spot. The speed of boat in still water is 12 km/hr. Find thespeed of the water current.

❏ Solution:-

✦Given:-

• Total time taken= 8 hours

• Total distance= (36×2) km.=72 km .

• Speed of Pratik in still water= 112 km/hr

✦To Find:-

• Speed of the water current=?

✦Explanation:-

Let, the speed of the water current = X km/hr.

∴Speed of Pratik in downstream=(12+X)km/hr.

∴ Speed of Pratik in upstream=(12-X)km/hr.

Hence,

➝Time taken in downstreaming=$\frac{36}{12+X}\:hrs$

➝Time taken in downstreaming=$\frac{36}{12-X}\:hrs$

Now, according to the problem total time taken is =8 hrs.

$\sf\therefore \frac{36}{12+X}+\frac{36}{12-X}=8$

$\sf\implies \cancel{36}\times\frac{(12-X)+(12+X)}{(12+X)(12-X)}=\cancel{8}$

$\sf\implies 9\times\frac{12-\cancel X+12+\cancel X}{12^2-X^2}=2$

$\sf\implies 9\times24=2\times(144-X^2)$

$\sf\implies 216=288-2X^2$

$\sf\implies 2X^2=288-216$

$\sf\implies X^2=\frac{\cancel{72}}{\cancel2}$

$\sf\implies X=\sqrt{36}$

$\sf\implies \boxed{\large{\red{X=6\:\:km.h^{-1}}}}$

∴ Speed of the water current is= 6 km/hr.

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$\underline{ \huge\mathfrak{hope \: this \: helps \: you}}$