quick question

D

Diablo3

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Dec 12, 2005
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3
This is the question in the Algebra 2 book.
Crew A loads books in 6 hours.
Crew B loads books in 4 hours.
A begins.
B begins 1 hour later.
How long does it take the job to get done?
I was told this over the phone & can't get it.
Thanks for you help in advance
 
Hello, Diablo3!

Crew A loads books in 6 hours. .Crew B loads books in 4 hours.

A begins. .B begins 1 hour later.

How long does it take the job to get done?
Click to expand...
Crew A can do the job alone in 6 hours.
. . In one hour, Crew A can do \(\displaystyle \frac{1}{6}\) of the job.
. . In \(\displaystyle x\) hours, Crew A can do \(\displaystyle \frac{x}{6}\) of the job. .(Get the idea?)

Crew B can do the job alone in 4 hours.
. . In one hour, Crew B can do \(\displaystyle \frac{1}{4}\) of the job.

Crew A begins and works for \(\displaystyle x\) hours; they do \(\displaystyle \frac{x}{6}\) of the job.

Crew B begins an hour late and works for \(\displaystyle x-1\) hours; they do \(\displaystyle \frac{x-1}{4}\) of the job.


Together, they do the whole job (1 job): \(\displaystyle \L\;\frac{x}{6}\,+\,\frac{x-1}{4}\:=\:1\)
. . and there is our equation!
 
Thanks. I can't believe I couldn't get that. It has been a while since I have messed with algebra.
 
Sorry, not 5. It can't take both of them longer than it would take B to do it alone. You have to multiply by the LCD of 12 and get
2x+3(x-1)=12
Can you take it from there?

BTW a good way to check your answer is to plug it into the original equation.
Code: 
5    5-1
-- + --- =? 1
6    4
 
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