Question 605828: please help me to solve this problem. Thanks.
If 30 laborers working 7 hours a day can finish a piece of work in 18 days, how many laborers working 6 hours a day can finish it in 30 days?
Answer by josmiceli(19441)   (Show Source):
You can put this solution on YOUR website! (1) 30 laborers working 7 hours a day can finish a piece of work in 18 days
(2) If they only work 1 hour a day, it will take them 7 times longer to finish, so
(3) 30 laborers working 1 hour a day can finish a piece of work in 126 days
(4) If they work 6 hours a day, It will take them 1/6 as long to finish
(5) 30 laborers working 6 hours a day can finish a piece of work in 21 days
(6) 7 times as many laborers can finish in 1/7 as many days, so
(7) 210 laborers working 6 hours a day can finish a piece of work in 3 days
(8) If they take 10 times longer to finish, they only need 1/10 as many laborers
(9) 21 laborers working 6 hours a day can finish a piece of work in 30 days
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