X, Y are two points in a river. Points P and Q divide the straight line XY into three equal parts. The river flows along XY and the time taken by a boat to row from X to Q and from Y to Q are in the ratio 4 : 5. The ratio of the speed of the boat downstream to that of the river current is equal to:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 10 : 3.
Let, the speed of the boat be 'x' km/hr and the current be 'y' km/hr
According to the question, the speed of the downstream = (2/4)a = (1/2)a
Also, the speed of downstream = (1/5)a
Thus,
⇒ x + y = (1/2)a & x - y = (1/5)a
Solving both the equation, we get, x = 7a km/hr and 3a km/hr
So the ratio of the speed of downstream and the current is 10 : 3