NumericalModerate3 marks
A man covers a distance of 100 km, travelling with a uniform speed of x km/hr. Had the speed been 5 km/hr more it would have taken 1 hour less. Find x the original speed.
Topic: Quadratic word problems
Previous-year question practice database
Answer
Exam answer
Original speed = 20 km/h.
Explanation
100/x − 100/(x+5)=1 ⇒ x(x+5)=500 ⇒ x²+5x−500=0 ⇒ x=20 km/h (positive root).
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