SOLUTION: A contractor hires two bulldozers to clear the trees from a 20 acre tract of land. One works twice as fast as the other. It takes them 3 days to clear the tract working together. H

Question 1153780: A contractor hires two bulldozers to clear the trees from a 20 acre tract of land. One works twice as fast as the other. It takes them 3 days to clear the tract working together. How long would it take each of them alone?
Found 2 solutions by josmiceli, greenestamps:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Call the clearing of 20 acres 1 job
Let = time in days for the faster worker to
do the job working alone
= time in days for the slower worker to do
the job working alone
------------------------------------------
[ 1 job ] / [ 3 days ] = their rate of woking together
Add their rates working alone to get their rate working together

Multiply both sides by

and

--------------------
The faster worker takes 4.5 days working alone
The slower worker takes 9 days working alone
--------------------
check:

Multiply both sides by

OK
Answer by greenestamps(13203) (Show Source): You can put this solution on YOUR website!

A very different way of solving the problem, which I find much easier and faster....

Since one of the bulldozers works twice as fast as the other, when working together one bulldozer does 2/3 of the work and the other does 1/3.

So the slower bulldozer does 1/3 of the job in 3 days, which means it will take it 9 days to do the job alone.

And the faster bulldozer works twice as fast, so it will take it half as long as the other to do the job alone -- 4.5 days.

ANSWERS:
4.5 days alone for the faster bulldozer
9 days alone for the slower

RELATED QUESTIONS
Question A) A company needs to clear 400ha of land. The company has newly acquired a D7 H (answered by akomfestus@gmail.com)
To bid competitively for the lumbering rights on a certain tract of land, a wood product... (answered by stanbon)
An acre is about 40,000 square feet, so you can imagine an acre to be a square area... (answered by ikleyn)
A contractor hires two trucking companies to haul 1600 tons of crushed stone for a... (answered by checkley77)
A 3-acre tract of land is for sale for $125,000, An individual wants a 150'*120 parcel.... (answered by Alan3354)
A newly cleared tract of land has been designated for reforestation. The commission... (answered by greenestamps)
Tom, Dick, and Harry begin working together to dig a trench. Tom works twice as fast as... (answered by ankor@dixie-net.com)
A square tract of land contains as many acres as there are boards in the fence enclosing... (answered by ikleyn)
Two pumps working together can fill a water tank in 18 minutes. one pump works twice as... (answered by lwsshak3)