A car covered a distance of 400 km at a uniform speed. If the uniform speed index is lowered by 10 km/h, the journey takes 2 hours longer. Find the original speed. MCQ with Answer and Explanation
A car covered a distance of 400 km at a uniform speed. If the uniform speed index is lowered by 10 km/h, the journey takes 2 hours longer. Find the original speed.
A. 60 km/h
B. 55 km/h
C. 50 km/h
D. 45 km/h
Answer: Option C
Solution (By JKSSB Mock Tests)
Let original speed be s. 400 / (s - 10) - 400 / s = 2 => 200 / (s - 10) - 200 / s = 1 => 2000 = s(s - 10). Solving s^2 - 10s - 2000 = 0 yields (s - 50)(s + 40) = 0. Original speed = 50 km/h.
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