X can do a piece of work in 40 days he works at it for 8 days and then why finished it in 16 days. How long will they take together take to complete the work
Solution
Correct Answer: Option B
Here, X can the work in 40 days. He works at it for 8 days and that means he's finished a fifth of the work (1/5). Now Y took 16 days to finish the rest of the work, which means he finished 4/5 th of the work in 16 days and will take 16 * 5/4 = 20 days to finish the work on a whole. X finishes 1/40 th of the work in one day. Y finishs 1/20 th of the work in one day. Since they work together their speeds add up and the time take t to complete the entire work W will be: t = W / (Speed of X + Speed of Y) = W / (W/40 + W/20) = 1/ (1/40 + 1/20) = (40 * 20) / (40 + 20) = 800/60 = 40 / 3
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