A thief escapes at 4:00 AM at 45 km/h. The police pursue him starting at 5:00 AM at 60 km/h. At what time will the thief be apprehended? MCQ with Answer and Explanation
A thief escapes at 4:00 AM at 45 km/h. The police pursue him starting at 5:00 AM at 60 km/h. At what time will the thief be apprehended?
A. 8:00 AM
B. 7:30 AM
C. 9:00 AM
D. 8:30 AM
Answer: Option A
Solution (By JKSSB Mock Tests)
By 5:00 AM, the thief has traveled for 1 hour and covered 45 km. Relative speed = 60 - 45 = 15 km/h. Time taken to catch = 45 / 15 = 3 hours. Capture time = 5:00 AM + 3 hours = 8:00 AM.
A car covered a distance of 200 km at a uniform speed. If the speed is reduced by 10 km/h, the time taken increases by 1 hour. Find the original speed.
Explanation:
Let original speed be s. 200 / (s - 10) - 200 / s = 1 => 200(s - s + 10) = s(s - 10) => 2000 = s(s - 10). Solving s^2 - 10s - 2000 = 0 gives (s - 50)(s + 40) = 0. Since speed is positive, s = 50 km/h.
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