A boat running downstream covers a distance of 10km in 3hr while for covering the same distance upstream, it takes 6hr.
What is the speed of the boat?
Choose the correct choice from the following options
A) 2.5 kmph  B) 3.5 kmph  C) 4.5 kmph  D) 1.5 kmph  E) 9.5 kmph

Rationale: speed upstream = 10 / 3 speed of boat down stream = 10 / 6 speed of boat = 1 / 2 ( 10 / 3 + 10 / 6 ) = 2.5 kmph answer : a
Answer: A