Question

answer me this question quick quick quick quick quick

Answer 1

Hello.
Let the usual time taken by the aeroplane = x km/hr
Distance to the destination = 1500 km
Case (i)
Speed = Distance / Time = (1500 / x) Hrs
 
Case (iI)
Time taken by the aeroplane = (x - 1/2) Hrs
Distance to the destination = 1500 km
Speed = Distance / Time = 1500 / (x - 1/2) Hrs
 
Increased speed = 100 km/hr
 
⇒ [1500 / (x - 1/2)] - [1500 / x] = 100
⇒ 1500(1/(x - 1/2) - 1/x) = 100
⇒ 1/(2x2 - x)=1/15
⇒ 2x2 - x=15
⇒ 2x2 - x -15=0
⇒ 2x2 -6x +5x -15=0
⇒ (2x -5)(x -3)=0
⇒ x = 3,-2/5
Since, the time can not be negative,
The usual time taken by the aeroplane = 3 hrs
and the usual speed = (1500 /3 ) = 500 km/hr.
Hope it helps.