A plane left 30 minutes late than its scheduled time and in order to reach the destination
Quadratic Equations (10)A plane left 30 minutes late than its scheduled time and in order to reach the destination 1500 km away in time, it had to increase its speed by 100 km/h from the usual speed. Find its usual speed.
Answer
Let the usual speed of the plane be x km/hr.
$$ \frac{1500}{x} - \frac{1500}{x + 100} = \frac{30}{60} $$
x2 + 100x - 300000 = 0
x2 + 600x - 500x - 300000 = 0
(x + 600)(x - 500) = 0
$ x \ne - 600, ∴ x = 500 $
Speed of plane = 500 km/hr
Exam Year:
2018
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