Does anyone know the formula to solve this word problem?
Gina can solve all the problems in a chapter in 12 hours and karen can in 16 hours, how long will it take them working together? I know the answer is 4.8 hours but I don't know how to get that answer

The answer is 6.857hrs. Gina's rate is 1/12 chapter per hour and Karen's is 1/16. Add their rates together to get 7/48 chapter per hour, which means 1 chapter would take 48/7 hours.

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Originally Posted by Kor214

The answer is 6.857hrs. Gina's rate is 1/12 chapter per hour and Karen's is 1/16. Add their rates together to get 7/48 chapter per hour, which means 1 chapter would take 48/7 hours.

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I really appreciate your help, but the answer is supposed to before.8 hours.

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Originally Posted by legomac

I really appreciate your help, but the answer is supposed to b 4.8 hours.

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Kor214 is correct. Either you made a mistake in entering the problem or the answer you have is incorrect. Think about it this way - the absolute least time it could ever take two people to accomplish what one could by herself is half the time of the fasted individual. So from the data you supplied the answer can not possibly be less than 1/2 of 12 hours, which is 6 hours.

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Originally Posted by ebaines

Kor214 is correct. Either you made a mistake in entering the problem or the answer you have is incorrect. Think about it this way - the absolute least time it could ever take two people to accomplish what one could by herself is half the time of the fasted individual. So from the data you supplied the answer can not possibly be less than 1/2 of 12 hours, which is 6 hours.

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Sorry, just learning how to do this. So how would you write this problem out using a formula? Its been 39yrs since I've done this stuff... lol

This formula will do it for you: Total time = 1/(1/T1 + 1/T2), where T1 and T2 are the times taken by each of the two individuals.