Ganesh Ujwal

The speed of the boat in still water is 22 kmph. It takes the same time for the boat to travel 1.2 km upstream as it does to travel 32km downstream. What is the speed of the current?

Solution: The overall speed of boat going downstream will be

speed downstream = 22 + c

The overall speed of boat going upstream will be speed of boat MINUS speed of current, because boat and current are pointing in opposite directions.

speed upstream = 22 – c

The typical equation for distance, rate, and time can be used.

distance downstream = rate downstream * time

32 km = (22 + c) * t

distance upstream = rate upstream * time

1.2 km = (22 – c) * t

It seems almost impossible to answer, since we do not know what t is. But you could solve each equation for t. Then equate the results, because same t value is used in both.

32 km / (22 + c) = t
1.2 km / (22 – c) = t

So if both things equal t, they equal each other.

32 km / (22 + c) = 1.2 km / (22 – c)

C = 20.4

But C value is 10 kmph. how to solve this problem ?

skipjack

It seems that the 1.2 km given in the problem should have been 12 km.

Ganesh Ujwal

why ?

skipjack

Because 12 km would lead to c = 10 km/h.

Denis

c = current speed

@22+c..........................32................. ...........>h hours [downstream]

@22- c............12...........>h hours [upstream]

32 / (22+c) = 12 / (22-c)

Solve for c