Question
Download Solution PDFA and B can together complete a task in 20 hours. After 5 hours, A leaves then B takes 45 hours to finish the remaining task. How many hours would A have taken to complete the entire task, if he worked alone from the beginning?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept used:
Total work = efficiency × time
Calculation:
According to the question,
20(A + B) = 5(A + B) + 45B
⇒ 15(A + B) = 45B
⇒ A + B = 3B
⇒ A = 2B
⇒ A/B = 2/1
So, total work = 20(A + B) = 20 × (2 + 1) = 60 unit
Now, A alone complete the work in = 60/2 = 30 hours
∴ The correct answer is 30 hours
Last updated on Jun 12, 2025
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