Question 227580
A supervisor can assemble 1000 toys in 4 days. A new employee takes 7 days to do the same job. How long will it take if they work together?
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S does 1000/4 toys per day
E does 1000/7 toys per day
Together, 1000/4 + 1000/7 per day
1000/4 + 1000/7 = 7000/28 + 4000/28 = 11000/28 per day
---> 28/11000 days per toy
= 28/11 days per 1000 toys
= ~ 2.545 days per 1000 toys
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The shortcut is product/sum
= 4*7/(4+7)
= 28/11