Question

a plane Left 30 minutes late than it's scheduled time and in order to reach the destination 1500km away in time,it had to increase its speed by 100 kilometers per hour find the usual speed

Answer 1

Hey mate...

Here's your answer...

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@Rêyaañ11

Answer 2

Sol:
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
⇒ 1/(2x2 - x) = 1/6
⇒ 2x2 - x = 6
⇒ (x - 2)(2x + 3) = 0
⇒ x = 2 or -3/2
Since, the time can not be negative,
The usual time taken by the aeroplane = 2 hrs
and the usual speed = (1500 / 2) =750 km/hr.