Question

a man can raw downstream 20 km in 2 h and up steram 4km in 2 hour find his speed in rawing in still water also find the speed of current​

Answer 1

Solution :-

Let his speed in rawing in still water and the speed of current be x km/hr and y km/hr respectively.

Case I : A man can raw downstream 20 km in 2 hr.

=> 20/(x + y) = 2

=> x + y = 10

=> x = 10 - y ______(i)

Case II : And upstream 4 km in 2 hr.

=> 4/(x - y) = 2

=> x - y = 2

=> 10 - y - y = 2 [from equation (i)]

=> 2y = 8

=> y = 8/2 = 4

Putting the value of y in equation (i) we get,

=> x = 10 - 4 = 6

Hence,

His speed in rawing in still water = 6 km/hr

The speed of current = 4 km/hr

Answer 2

Answer:-

Speed rawing in still water speed becurrent be x km/hr

Downstream raw a man can =20 km in 2 hr.

$\frac{20}{x + y} {} = 2 \\ </p><p>x + y = 10 \\ </p><p>x = 10 - y$

4 km in 2 hr is the upstream

$\frac{4}{x - y} = 2 \\ </p><p>x - y = 2 \\ </p><p>10 - y - y = 2 \\ </p><p>2y = 8 \\ </p><p>y = \frac{8}{2} = 4</p><p>$

Value of y in equation

$(x = 10 - 4 = 6)$

Therefore

The man's speed in rawing in still water = 6 km/hr and Speed of current

$= (4 km/hr)$