In a 500-meter dash trial heat, runner A clocks across the tape in 50 seconds, while runner B marks a finish layout in 55 seconds. By what distance does runner A beat runner B? MCQ with Answer and Explanation
In a 500-meter dash trial heat, runner A clocks across the tape in 50 seconds, while runner B marks a finish layout in 55 seconds. By what distance does runner A beat runner B?
A. 42.34 meters
B. 45.45 meters
C. 48.25 meters
D. 50.00 meters
Answer: Option B
Solution (By JKSSB Mock Tests)
Speed of runner B = 500 / 55 = 100 / 11 m/s. Distance covered by runner B when runner A finishes at 50 seconds = (100 / 11) * 50 = 5000 / 11 = 454.54 meters. Margin distance = 500 - 454.54 = 45.45 meters.
Explanation:
New speed = 6/7 of normal pace => New time = 7/6 of normal time. Difference = 1/6 of normal time = 12 minutes. Normal time = 12 * 6 = 72 minutes.
A man covers 3/5 of his journey at 60 km/h, 1/4 of his journey at 40 km/h and the remaining journey at 20 km/h. Find his average speed for the whole transaction.
Explanation:
Let total distance be 400 km. First part = 240 km; Time = 240/60 = 4 hours. Second part = 100 km; Time = 100/40 = 2.5 hours. Remaining distance = 400 - 240 - 100 = 60 km; Time = 60/20 = 3 hours. Total time = 4 + 2.5 + 3 = 9.5 hours. Average speed = 400 / 9.5 = 4000 / 95 = 46.15 km/h.
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