In a fixed time, a boy swims double the distance along the

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In a fixed time, a boy swims double the distance along the current that he swims against the current. If the speed of the current is 3 km/hr, the speed of the boy in still water is

1. 6 km/hr
2. 9 km/hr
3. 10 km/hr
4. 12 km/hr

Correct Option: B

Let the rate of swimming in still water be p kmph
∴ Rate down-stream = (p + 3) kmph
∴ Rate up-stream = (p – 3) kmph
According to the question,
(p + 3) t = 2 (p – 3) × t
⇒ p + 3 = 2p – 6
⇒ p = 9 kmph
Using the given formula :
Here, t₁ = 2k , t₂ = k
Speed of Stream = 3 km/hr

∴	Speed of Boy	=	t₁ + t₂
	Speed of Stream		t₁ - t₂

	Speed of Boy	=	2k + k
	3		2k - k

Speed of Boy = 9 km/hr