RRB NTPC CBT-1 previous year question
A, B, and C can complete a work in 10, 12, and 15 days, respectively. A and B work together for 3 days, after which A withdraws. B and C then work together. Find the number of days required by B and C to complete the remaining work.
Asked in RRB NTPC 2026 — 15 June Shift 3 · Quantitative Aptitude
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Correct answer: (B) 3 days
A, B, and C's rates are 1/10, 1/12, 1/15. In 3 days, A and B together complete 3×(1/10+1/12)=11/20 of the work, leaving 9/20. B and C together work at 1/12+1/15=3/20 per day, so they need (9/20)/(3/20)=3 days.
हिंदी में प्रश्न
A,B और 10,12 किसी कार्य को क्रमशः 15 और 3 दिनों में पूरा कर सकते हैं। & और 8 मिलकर 3 दिन कार्य करते हैं, जिसके बाद A कार्य छोड़ देता है। 8 और ० मिलकर कार्य करते हैं। शेष कार्य को पूरा करने के लिए 8 और ० को कितने दिन लगेंगे?
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सही उत्तर: (B) 3दिन
A, B, और C की दरें 1/10, 1/12, 1/15 हैं। 3 दिन में A और B मिलकर 3×(1/10+1/12)=11/20 कार्य पूरा करते हैं, शेष 9/20 बचता है। B और C मिलकर 1/12+1/15=3/20 प्रतिदिन काम करते हैं, अतः उन्हें (9/20)/(3/20)=3 दिन चाहिए।
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