Question
Download Solution PDFIn a computer game, a builder can build a wall in ten hours while a destroyer can demolish such a wall completely in fourteen hours. Both the builder and the destroyer were initially set to work together on the ground level, but, after 7 hours, the destroyer was taken out. What was the total time (in hours) taken to build the wall?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFLet the total work required to build a wall be 70 units (LCM of 10 and 14).
⇒ Work done by a builder in 1 hour = 70/10 = 7 units.
⇒ Work done by destroyer in 1 hour = 70/-14 = -5 units.
⇒ Total work done in 1 hour = 7 – 5 = 2 units
Work done by both of them = 2 × 7 = 14 units
Remaining work = 70 - 14 = 56 units
Remaining work was done by the builder.
∴ Time required = 56/7 = 8 hours
Total time required = 8 + 7 = 15 hours
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