A boat covers 12 km upstream and 18 km downstream in 3 hours,

A boat covers 12 km upstream and 18 km downstream in 3 hours, while it covers 36 km
upstream and 24 km downstream in 6 1 hours. What is the speed of the current ?
2

Let the speed of boat in still water be p kmph and that of current be q kmph, then

	12	+	18	= 3 .........(i)
	p - q		p + q

	36	+	24	=	13	.........(ii)
	p - q		p + q		2

By equation (i) × 3 – equation (ii),

	54	-	24	= 9 -	13
	p + q		p + q		2

⇒	30	=	5	⇒ p + q = 12......(iii)
	p + q		2

From equation (i),

⇒	12	+	18	= 3
	p - q		12

⇒	12	= 3 -	3	=	3
	p - q		2		2

⇒ p - q =	12 × 2	= 8.......(iii)
	3

∴ Speed of current =	1	(12 - 8) = 2 kmph
	2

upstream and 24 km downstream in 6	1	hours. What is the speed of the current ?
	2