Question

a plane left 30 minutes later than to schedule time and its order to reach of destination 1500 km away in time it had to increase its speed by hundred kilometre per hour from the usual speed

Answer 1

Answer:

Step-by-step explanation:Let the usual time taken by the aeroplane = x km/hr

Distance to the destination = 1500 km

--------Speed = Distance / Time = (1500 / x) Hrs

 

------------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

 150((10/x-1/2)-10/x0=100

 15 /x -1/2- 15/x =1 

30x -30x +15=2x^2-x

15=2x^2-x

2x^2-x-15=0

2x^2 - 6x+5x-15=0

2x(x-3)+5(x-3)

2x+5=0  or x-3 =0

x=-5/2   or x=3

Since, the time can not be negative,

The usual time taken by the aeroplane = 3hrs

and the usual speed = (1500 / 3) = 500km/hr