SOLUTION: Batman can clean up all of the crime in Gotham cityin 8 hours working alone. Robin can do the same job in 12 hours working alone. If Robin starts fighting crime at 8 A.M. and Batma
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-> SOLUTION: Batman can clean up all of the crime in Gotham cityin 8 hours working alone. Robin can do the same job in 12 hours working alone. If Robin starts fighting crime at 8 A.M. and Batma
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Question 8356: Batman can clean up all of the crime in Gotham cityin 8 hours working alone. Robin can do the same job in 12 hours working alone. If Robin starts fighting crime at 8 A.M. and Batman joins him at 10 A.M. then at what time will they have all the crime cleaned up? Answer by Earlsdon(6294) (Show Source):
You can put this solution on YOUR website! Let's find out how much these super-heros can accomplish in 1 hour.
Batman (B) can do the job in 8 hours, which means he can do 1/8 of the job in 1 hour.
Robin (R) can do the same job in 12 hours, which means he can do 1/12 of the job in 1 hour.
Working together then, B & R can do 1/8 + 1/12 (5/24) of the job in 1 hour.
Robin starts at 8:00 am and, by the time he is joined by Batman at 10:00 am, he has done 2hrs(1/12) or 1/6 of the job. This means that there is 5/6 of the job left for the Dynamic Duo to finish the clean-up of Gotham city.
Together, our heroes can do 5/24 of the job in 1 hour. There is 5/6 or 20/24 of the job left to do.
So an additional 4 hours will be required after Batman shows up for work.
Add this to the 2 hour already put in by the Boy Wonder, and you have a total of 6 hours for the total clean up.
8:00 am + 6 hours puts us at 2:00 pm. and just in time for tea!
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