Consider a boat which moves at the speed of 6 km/hr. If the water runs at the speed of about 4 km/hr, then the boat requires 3 hours to reach a certain place and return. Calculate the distance between that place & boat's initial position.
10 km
5 km
15 km
4 km
Explanation:
Distance between two places =$\dfrac{t\left(x^2-y^2\right)}{2x}$
Given parameters are:
Speed of boat (x) = 6 km/hr
Speed of water (y) = 4 km/hr
Time taken by the boat to go & return back = t = 3 hrs
To find the distance between the place & initial position of boat (i.e. between two places), we have
Distance between two places =$\dfrac{t\left(x^2-y^2\right)}{2x}$
=$\dfrac{3\left(6^2-4^2\right)}{2\times6}$
=$\dfrac{3\left(36-16\right)}{12}$
=$\dfrac{\left(3\times20\right)}{12}$
=5km/hr