If the speed of boat in still water is 10 km/hr & the speed of stream is 3 km/hr, the boat rows to a place which is 50 km far & returns through the same path. What would be the average speed of boat during the journey?
9.1 km/hr
8.1 km/hr
7.1 km/hr
6.1 km/hr
Explanation:
Given Parameters :
Speed of boat in still water = x = 10 km/hr
Speed of stream = y = 3 km/hr
We have,
Average Speed=$\dfrac{\left(x^2-y^2\right)}{x}km/h$
=$\dfrac{\left(10^2-3^2\right)}{10}km/h$
=$\dfrac{\left(100-9\right)}{10}km/h$
=9.1km/hr