If a man travel's by his motor boat down a river to his office and back. With the speed of the river unchanged, if he doubles the speed of the boat, then his total travel time gets reduced by 75%. The ratio of the original speed fo the boat to speed of the river is ?
The boat problem usually has 3 components to it
- speed of the river
- speed of the boat
- time to cover the distance (one way/round trip)
Downstream speed would be
And upstream speed would be
The time taken to complete the round trip would be
If speed of the boat is doubled, time reduces by 75% (i.e its 25% of original time)
Let's make T 100% in the equation
The distance can be removed from both LHS and RHS
Let's try to reduce the equations.
And reduce it even further
Moving the sides around we get
The ratio of the squares would be.