uestion hmers2 to br cui25. A plane left 30 minutes later than the schedule time. In order to reach its destination1500 km away in time, it has to increase the speed by 250 km/hr. Find its usual speed.

uestion hmers2 to br cui25. A plane left 30 minutes later than the sch

1.	uestion hmers2 to br cui25. A plane left 30 minutes later than the schedule time. In order to reach its destination1500 km away in time, it has to increase the speed by 250 km/hr. Find its usual speed.
Answer» Sol:Let the usual time taken by the aeroplane = x km/hrDistance to the destination = 1500 kmCase (i)Speed = Distance / Time = (1500 / x) HrsCase (iI)Time taken by the aeroplane = (x - 1/2) HrsDistance to the destination = 1500 kmSpeed = Distance / Time = 1500 / (x - 1/2) HrsIncreased speed = 250 km/hr⇒ [1500 / (x - 1/2)] - [1500 / x] = 250⇒ 1/(2x2- x) = 1/6⇒ 2x2- x = 6⇒ (x - 2)(2x + 3) = 0⇒ x = 2 or -3/2Since, the time can not be negative,The usual time taken by the aeroplane = 2 hrsand the usual speed = (1500 / 2) = 750 km/hr.