SOLUTION: Two harvesting machines can each harvest a field in 15 hrs. If they are joined by a newer machine and the three machines work together, the job takes 3 hrs. How long would it talk
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-> SOLUTION: Two harvesting machines can each harvest a field in 15 hrs. If they are joined by a newer machine and the three machines work together, the job takes 3 hrs. How long would it talk
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Question 121892This question is from textbook
: Two harvesting machines can each harvest a field in 15 hrs. If they are joined by a newer machine and the three machines work together, the job takes 3 hrs. How long would it talk for the newer machine to harvest the field alone?
i have not a clue where to start...im so bad at story problems..i can do the problems and get algebra but i never know what to do with story problems and how to set them up? This question is from textbook
You can put this solution on YOUR website! Two harvesting machines can each harvest a field in 15 hrs. If they are joined by a newer machine and the three machines work together, the job takes 3 hrs. How long would it take for the newer machine to harvest the field alone?
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Let x = the time the newer machine needs to complete the job alone
Let the completed job = 1
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Each machine will do a fraction of the work
All three will work for 3 hrs so we can say:
Each original machine will 3/15
The new machine: 3/x
Remember the completed job = 1:
: + + = 1
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we can simplify this the 1st two machine = 6/15 reduced to 2/5
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Now we have a real simple equation: + = 1
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Multiply the equation by 5x to get rid of the denominators
5x* + 5x = 5x(1)
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Cancel out the denominators and we have:
2x + 15 = 5x
15 = 5x = 2x
15 = 3x
x =
x = 5 hrs for the new machine to do it alone.
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Check solution in the original equation
3/15 + 3/15 + 3/5 =
1/5 + 1/5 + 3/5 = 1; confirms our solution
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Hopefully this provided a few clues, did it make sense to you? Any questions?
