Q- While boarding an aeroplane, a passenger got hurt. The pilot showing promptness and concern, made arrangements to hospitalise the injured and so the plane started late by 30 minutes. To reach the destination , 1500 km away , in time, the pilot increased the speed by 100 km/ hr. Find the original speed / hour of the plane. Do you appreciate the values shown by the pilot, namely promptness in providing help to the injured and his efforts to reach in time ?
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Step-by-step explanation:
Let the Original speed of the aeroplane be x km/h.
Time taken to cover 1500 km with the usual speed of x km/h = 1500 / x hrs
Time taken to cover 1500 km with the increase speed of (x+100) km/h = 1500 / (x+100) hrs
ATQ
1500 / x = 1500 / (x+100) + ½
1500 / x - 1500 / (x+100) = ½
1500(x+100) -1500x / x(x+100)= ½
1500x + 1500 × 100 -1500x / x² +100x = ½
1500 × 100 / x² +100x = ½
2(1500 × 100 ) = x² + 100x
300000 = x² +100x
x² +100x - 300000 =0
x² - 500 x + 600 x - 300000= 0
x(x - 500) + 600(x - 500)= 0
(x+600) (x - 500) = 0
(x+600) = 0 or (x - 500) = 0
x = -600 or x = 500
Speed cannot be negative, so x = 500
Hence the usual speed of the plane is 500 km/h.
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