SOLUTION: It takes Nina 3 hours to proof a chapter of Hawkes Learning Systems' Statistics book and it takes Cynthia 12 hours. How long would it take them together?

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Question 602969: It takes Nina 3 hours to proof a chapter of Hawkes Learning Systems' Statistics book and it takes Cynthia 12 hours. How long would it take them together?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

It takes Nina 3 hours to proof a chapter of Hawkes Learning Systems' Statistics

 book and it takes Cynthia 12 hours.

Let x represent the time it would take them together

Note: job / hour is the key

 1/3 + 1/12 = 1/x       |Multiplying thru by 12x so as all denominators = 1

4x + x = 12

   5x = 12

    x = 2.4 hrs, the time it would take them together