RRB Technician Grade 3 previous year question
A car travels 120 km at an unknown speed x km/h and then returns at (x + 20) km/h. The average speed for the whole journey is 60 km/h. Find the value of x. (Round to one decimal place.)
Asked in RRB Technician Grade 3 (09 Mar 2026 Shift 3) · Quantitative Aptitude
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Correct answer: (B) 51.6
Average speed formula 2x(x+20)/(2x+20)=60 leads to the quadratic x²−40x−600=0, giving x = (40+√4000)/2 ≈ 51.6.
हिंदी में प्रश्न
एक कार x km/h की अज्ञात चाल से 120 km की यात्रा करती है और फिर (x + 20) km/h की चाल से वापस लौटती है। संपूर्ण यात्रा की औसत चाल 60 km/h है। x का मान ज्ञात कीजिए। (उत्तर को एक दशमलव स्थान तक पूर्णांकित कीजिए)
उत्तर जाँचने के लिए किसी विकल्प पर टैप करें।
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सही उत्तर: (B) 51.6
औसत चाल सूत्र 2x(x+20)/(2x+20)=60 से द्विघात समीकरण x²−40x−600=0 प्राप्त होता है, जिससे x = (40+√4000)/2 ≈ 51.6।
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