SOLUTION: In a flight of 2800 km , an aircraft was slowed down due to bad weather . Its average speed for the trip was reduced by 100km per hour and time icreased by 30 minutes . Find the or

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Question 32118: In a flight of 2800 km , an aircraft was slowed down due to bad weather . Its average speed for the trip was reduced by 100km per hour and time icreased by 30 minutes . Find the original duration of flight ?
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
Let the average speed be x
When it is decreased it will be: x-100
and time increased by 30 minutes or 0.5 hours:
TOtal distance of flying wil respect to speed and time = 2800
Equation:

Cross multiply

2800[(x)-(x-100)]=0.5[(x)(x-100)]

2800%28100%29=0.5%28x%5E2-100x%29

0.5x%5E2-50x-280000

Multiply the eqauiton by 2 to remove the decimal:

x%5E2-100x-560000=0

 

In quadratic equation: a=1, b=-100, c=-560000



Simplfy 

x=-700 or x=800

Hence, the average speed was 800km/h.

Paul.