RRB ALP practice question
In a 500 m race with no head start, A beats B by 100 m. If instead A gives B a start of 5 seconds, the race ends in a dead heat. Find A's speed.
From a RRB ALP Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (A) 25 m/s
With no head start, when A covers 500 m, B covers only 400 m, so B's speed = (4/5) x A's speed. With a 5 s time start giving a dead heat: 500/b - 500/a = 5. Substituting b = 0.8a: 500/(0.8a) - 500/a = 5 => 625/a - 500/a = 5 => 125/a = 5 => a = 25 m/s.
हिंदी में प्रश्न
बिना किसी शुरुआत के 500 मीटर की दौड़ में A, B को 100 मीटर से हराता है। यदि इसके बजाय A, B को 5 सेकंड की शुरुआत देता है, तो दौड़ डेड हीट में समाप्त होती है। A की चाल ज्ञात कीजिए।
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सही उत्तर: (A) 25 मीटर/सेकंड
बिना शुरुआत के, जब A 500 मीटर तय करता है, तब B केवल 400 मीटर तय करता है, अतः B की चाल = (4/5) x A की चाल। 5 सेकंड की शुरुआत से डेड हीट होने पर: 500/b - 500/a = 5। b = 0.8a रखने पर: 500/(0.8a) - 500/a = 5 => 625/a - 500/a = 5 => 125/a = 5 => a = 25 मीटर/सेकंड।
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