When a stone is dropped from a building 200 m high, its speed is proportional to the time elapsed after dropping. The distance traveled is proportional to the square of the time elapsed. After 1 second the speed of the train was 10 m/sec and it was 190 m above the ground. When its speed is 25 m/sec, what would be its distance from the ground? Choose the correct choice from the following choices
A) 140 m	B) 137.5 m	C) 125.75 m	D) 142.5 m	E) 152.5 m

Rationale: v = x * t and s = y * t ^ 2 10 = x * 1 , hence x = 10 units ( 200 - 190 ) = y * 1 * 1 y = 10 when speed = 25 m / sec , time elapsed = 25 / 10 = 2.5 sec distance travelled by stone = 10 * ( 2.5 ) ^ 2 = 62.5 mts so distance of stone above ground = 200 - 62.5 = 137.5 mtrs answer : b
Answer: B