SOLUTION: One person can do a job in 8 hours. A second person can do it in 12 hours. If the first person works 2 hours less than the second, how many hours will it take them working together
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Question 91870This question is from textbook algebra and trigonometry
: One person can do a job in 8 hours. A second person can do it in 12 hours. If the first person works 2 hours less than the second, how many hours will it take them working together? PLEASE HELP
This question is from textbook algebra and trigonometry
Found 2 solutions by stanbon, mathispowerful:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
One person can do a job in 8 hours. A second person can do it in 12 hours. If the first person works 2 hours less than the second, how many hours will it take them working together?
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One person DATA;
Time = 8 hr/job ; Rate = 1/8 job/hr
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Second person DATA:
Time = 12 hr/job ; Rate = 1/12 job/hr
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Time on this job:
2nd person works x hours.
1st person works x-2 hours.
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EQUATION:
x(1/12) + (x-2)(1/8) = 1 job
Multiply thru by 24 to get:
2x + 3(x-2) = 24
2x + 3x-6 = 24
5x = 30
x = 6 hrs (how long 2nd person works)
x-2 = 4 hours (how long 1st person works)
==============
Cheers,
Stan H.
Answer by mathispowerful(115) (Show Source): You can put this solution on YOUR website!
Assume it takes them T hours working together.
then in one hour the first person can finish
the second person can finish in the same one hour
working together, the first person will spend T-2 hours, the second person will spend T hours
the portion finished by first person is
the portion finished by second person is
together they finish the whole thing represented by 100% which is 1
so we have
multiply both sides by 24 we get
3(T-2) + 2T = 24
solve this equation we get T = 6 hrs.
( I assume you know how to solve one variable equation)
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