Question

A stone is thrown vertically upward with velocity u such that the distances travelled by it in the 5th second and 9th second are equal. The distance travelled by the stone in the 7th second is [g = 10 m/s2]

Answer 1

Well its a hunch. You see what I did was that , according to the question, its written there that the distance covered in the 5 and 9 sec are equal, and in between 5 and 9 there is 7 .
So the highest point attained by the projectile would be at the 7 sec.
now at the highest point v would be zero. hence from the equation
$v = u \: + at$
u becomes 70 m/sec
distance travelled would come out to be feom the formula
$v ^{2} = {u}^{2} + 2as$
s = (4900)/2*10 = 245 meters