An aero plane flying with the wind cover a certain distance in 2 hrs the return trip against the wind takes 2.5 hrs. How fast is the plane, if the one –way distance is 600 miles? (In miles/hour)

A 270

B 30

C 240

D 60

E 250

Correct Answer: Option A

Let the speed of the plane be x miles/hrs

Let the speed of the wind be y miles/hrs

Speed = distance/time

Speed of plane against wind = x - y

Speed of plane with wind = x + y

\(\begin{array}{l} \therefore \frac{{600}}{{x - y}} = 2.5\\ \therefore \frac{{600}}{{x - y}} = \frac{5}{2} \end{array}\)

∴ 240 = x - y ….(i)

∴ 600 / (x + y) = 2

∴ x + y = 300 ….(ii)

Adding (i) and (ii)

∴ 2x = 540

∴ x = 270

∴speed of plane = 270 miles/hrs