Question

If the spped of an aeroplane is reduced by 40 km per hr, it takes 20 minutes more to cover 1200 km. Find the speed of the aeroplane.

Answer 1

Let speed of the aeroplane = v km/hr

distance = 1200 km

time= t hr

Now according to the given conditions

v = 1200/t ...... (1)

v - 40 = 1200/ (t +1/3) ...... (2) (since 20 mins= 1/3 hour)

Put value of v from (1) into (2) we get

t = -3.31 or 2.985

and fot t=2.985 we get

v=402.01km / hr