UP TGT Mathematics Commercial Mathematics Test Series - Part 4
A car covers a distance of 840 km at a constant speed. If the speed had been 10 km/h more, it would have taken 2 hours l...
Type: MCQ • Marks: 1
A car covers a distance of 840 km at a constant speed. If the speed had been 10 km/h more, it would have taken 2 hours less to cover the same distance. Find the original speed of the car.
Options
A. 1) 80 km/h
B. 2) 50 km/h
C. 3) 70 km/h
D. 4) 60 km/h
Explanation
Let speed be S. 840/S - 840/(S+10) = 2 => 840 * 10 / (S*(S+10)) = 2 => S(S+10) = 4200 => S^2 + 10S - 4200 = 0 => (S+70)(S-60) = 0 => S = 60 km/h.
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