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In a flight of 28000 km …

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In a flight of 28000 km an aircraft was slowed down due to bad wx condition. It's avg speed is reduced by 100km/h and time is increased by 30minute. Find the original duration of the flight
  • 1 answers

Yogita Ingle 5 years, 11 months ago

speed of aircraft= x
Distance = 2800 km


Time = Distance / Speed = 2800/x
Given:

The speed has reduced by 100 and time is reduced by 30 min


New speed = (x – 100)
That is, 30 min = 30/60 hr = (1/2) hr
Time taken= 2800/(x – 100) hr
=2800/(x – 100)

= (2800/x) + (1/2)
2800/(x-100) -` (2800/x)  =  1/2

x² - 100x - 560000  = 0

x² - 800x + 700x - 560000  =  0

x(x - 800) + 700(x - 800)  =  0
(x + 700) (x - 800)  =  0
SO,

x  =  - 700 or 800

Thus original duration of the flight =  2800/800 = 7/2 hours
OR = 3 hr 30 mins

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