A car traveling at a uniform speed covers 300 km. If the speed had been 10 km/h more, it would have taken 1 hour less. Find the initial speed. MCQ with Answer and Explanation
A car traveling at a uniform speed covers 300 km. If the speed had been 10 km/h more, it would have taken 1 hour less. Find the initial speed.
A. 55 km/h
B. 60 km/h
C. 45 km/h
D. 50 km/h
Answer: Option D
Solution (By JKSSB Mock Tests)
Let original speed be s. 300 / s - 300 / (s + 10) = 1 => 300(10) = s(s + 10) => 3000 = s(s + 10). Solving s^2 + 10s - 3000 = 0 gives (s - 50)(s + 60) = 0. Since speed is positive, s = 50 km/h.
Explanation:
When A covers 200m, B covers 180m and C covers 162m. This means in a match distance where B covers 180 meters, C covers 162 meters. Scaling down to 90 meters: B covers 90m, C covers 162 * (90/180) = 81m. Therefore, B beats C by 90 - 81 = 9 meters.
Explanation:
Relative speed = 140 / 12 = 35/3 m/s = (35/3) * (18/5) = 42 km/h. Since both walk/move in the same direction, Relative Speed = Speed of train - Speed of pedestrian => 42 = Speed of train - 4 => Speed of train = 46 km/h.
No comments yet. Be the first to start the discussion!