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Question 51346This question is from textbook college algebra
: Question for help...Thanks
"Batman and Robin" Batman can clean up all of the crime in Gotham city in 8hr working alone. Robin can do the same job alone in 12hr. If Robin starts crime fighting at 8 A.M and Batman joins him at 10 A.M, then at what time will they have all of the crime cleaned up??
This question is from textbook college algebra
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Batman can clean up all of the crime in Gotham city in 8hr working alone. Robin can do the same job alone in 12hr. If Robin starts crime fighting at 8 A.M and Batman joins him at 10 A.M, then at what time will they have all of the crime cleaned up??
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Batman DATA:
time = 8 hr/job ; rate = 1/8 job/hr
Robin DATA:
time= 12 hr/job ; rate = 1/12 job/hr
EQUATION:
Robin work plus Together work = 1 job
2hr(1/12)job/hr+xhr.(1/8+1/12)job/hr = 1 job
(1/6)+x(20/96)=1
16+20x=96
20x=80
x=4 hrs.
They will be finished at 10 A.M. + 4 hours = 2:00PM
cheers,
Stan H.
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