RRB Technician Grade 3 practice question
A train passes two persons walking in the same direction as the train at 4.5 km/h and 9 km/h in 24 seconds and 28 seconds respectively. What is the speed of the train?
From a RRB Technician Grade 3 Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (A) 36 km/h
Let train speed v km/h, length L m. L = (v − 4.5) × 5/18 × 24 = (v − 9) × 5/18 × 28. So 24(v − 4.5) = 28(v − 9) ⇒ 4v = 144 ⇒ v = 36 km/h. Then L = (36 − 4.5) × 24 × 5/18 = 756 × 5/18 = 210 m. Answer: 36 km/h.
हिंदी में प्रश्न
एक रेलगाड़ी अपनी दिशा में 4.5 किमी/घंटा और 9 किमी/घंटा की चाल से चल रहे दो व्यक्तियों को क्रमशः 24 सेकंड और 28 सेकंड में पार करती है। रेलगाड़ी की चाल क्या है?
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सही उत्तर: (A) 36 किमी/घंटा
माना रेलगाड़ी की चाल v किमी/घंटा और लंबाई L मी। L = (v − 4.5) × 5/18 × 24 = (v − 9) × 5/18 × 28। अतः 24(v − 4.5) = 28(v − 9) ⇒ 4v = 144 ⇒ v = 36 किमी/घंटा। तब L = (36 − 4.5) × 24 × 5/18 = 756 × 5/18 = 210 मी। उत्तर: 36 किमी/घंटा।
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