- A7.2 days7.2 दिन
- B7.5 days7.5 दिन
- C7.8 days7.8 दिन
- D7.4 days7.4 दिन
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Concept: Take total work = LCM of days; find what is left after P works alone.
- Work = 60 units; P = 3/day, Q = 2/day.
- P in 8 days = 24 → left 36.
- Together 5/day → 36 ÷ 5 = 7.2 days.
Trick: Fraction way: P does 8/20 = 2/5; remaining 3/5 ÷ (1/20 + 1/30 = 1/12) = 36/5 = 7.2.
Answer: (A) 7.2 days
अवधारणा: कुल कार्य = दिनों का LCM; P के अकेले काम के बाद शेष कार्य निकालें।
- कार्य = 60 इकाई; P = 3/दिन, Q = 2/दिन।
- P 8 दिन में = 24 → शेष 36।
- दोनों मिलकर 5/दिन → 36 ÷ 5 = 7.2 दिन।
ट्रिक: भिन्न विधि: शेष 3/5 ÷ (1/12) = 36/5 = 7.2 दिन।
उत्तर: (A) 7.2 दिन
