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on my review I need to understand for my end of the year unit test thanksTwo Algebra...

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on my review I need to understand for my end of the year unit test thanks

Two Algebra teachers are grading papers. It takes Dr. H 3 hours to grade 50 papers and it takes the other Algebra teacher 4 hours to grade 50 papers. If they both work together how long will it take them to grade 50 papers?

Posted by b-bug3411 on May 14, 2012 at 2:25 PM via web and tagged with math, math/ algebra help...confused need help

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An important rule while working in Algebra, we do not like decimal approximation in the begining of the problem. It can lead to a large margin of error. Fraction lowest term is what you need to work with, you can estimate the answer at the end if asked.

Dr H. rate=50/3 paper per hour

Alg teacher rate 50/4=25/2 paper per hour

Working together, they should finish `(50/3+25/2)=(100+75)/6=175/6`  paper per hour

`Rate=(#paper)/(time) => time=(# paper)/(rate)`

time=`50/(175/6)=(50*6)/175=(2*25*6)/(25*7)=12/7=1 5/7hour`

You can write an approximation of the time that involve minutes if you chose to answer will be

1 hour (5/7)*60 minutes which give an approximately 1hour 43 minutes.

Posted by rcmath on May 14, 2012 at 10:17 PM (Answer #1)