T&W q2

[Saumyojit]

20 workers can finish a work in 30 days. After how many days should 5 workers leave the job so the work is completed in 35 days?


20 workers per day work = 1/30
x/30 + 15 workers per day work * (35-x)= 1
(x + 1050 * 15 workers per day work - 30 * 15 workers per day work * x ) /30 =1
x +15 workers per day work * (1050 - 30x) = 30
What is the per day work of 15 workers =

per day work of 20 workers= 1/30
per day work of 1worker = 1/(30 * 20)= 1/60
per day work of 15 workers = 15 * 1/60 = 0.25 ?

 

[Dr.Peterson]

per day work of 1worker = 1/(30 * 20)= 1/60

Please check your work before posting it!

 

[Steven G]

Please define YOUR variables.

I would let x = the number of days before any workers left.

So, 20-5=15 workers worked for 30 day
5 workers worked x days.

20 workers can finish a job in 30 days. So 1 worker can finish the job in 600 days. Hence each worker does 1/600 of the job per day.

15 workers for 30 days will do 15*30/600 of the job
5 workers for x days will 5x/600 of the job.

So 5x/600 will be 1/4 of the job