SOLUTION: 28 workers can finish a piece of work in 45 days. a)How many workers are needed if the work is to be done in 36 days? b)If after 33 days, 7 of the 28 workers leave, calculate the

Question 815308: 28 workers can finish a piece of work in 45 days.
a)How many workers are needed if the work is to be done in 36 days?
b)If after 33 days, 7 of the 28 workers leave, calculate the number of days that the rest of the workers require to finish the work.
the answer of a) is 35 but i could not solve b)

Found 2 solutions by richwmiller, rothauserc:
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
28*45=1260 man days
a)1260/36=35 workers to finish in 36 days
b) 33*28=924
1260-924=336 work days to go
28-7=21
336/21=16 more days to finish the job

Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
a) (28/45) / 28 tells us how much each worker contributes to the work
let x be the number of workers required to complete the same amount of work in 36 days, therefore
let u = ((28/45) / 28)
u * 28 * 45 = u *x *36
cancel the u from both sides of the =
28*45 = 36x
x = 35 workers
b) (u * 28 *33) + (u * 21 * x) = (u * 28 * 45)
cancel u from both sides of =
(28*33) + 21x = 28*45
21x = 336
x = 16
rest of workers take 16 days to finish the job

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