Question

If speed of a aeroplane is reduced by 40km per hr,it takes 20 min more to cover 1200km.find the speed of the aeroplane

Answer 1

the speed of the aeroplane is 400km/hr

Answer 2

Let the actual speed of aeroplane = x km/hr 

speed after reduction = (x-40) km /hr

let actual time taken = y hr

and 

time taken after = y+ 20 min = y+(20/60)=

Distance = 1200km 

therefore , acc. to the question,

Distance = Speed × Time 

1200 = x × y......(i)

and ...
Answer is 400 km/h.