Question

Shawn and Ellie are construction workers. Shawn can complete a concrete job in 5 hours, while Ellie can complete it in 7 hours. The foreman says that it will take them 6 hours to complete it if they work together, explaining you just add the hours for each worker and divide by 2. Explain each step in solving this equation, and determine if the foreman is correct or not.

Answer 1

Shawn can finish 1/5 of the job in 1 hour, and Ellie can do 1/7. Add 1/5 + 1/7 which is 12/35. If you turn that to a decimal, you get about .34. You could round that to 3 because .34 times 3 = 1.02, or about 1. So it would take them about 3 hours. The foreman was incorrect because he was looking for the mean hours between them, so he is wrong. If you need an exact answer, then I can't help you with that.

Answer 2

Yes the worker is correct.

Explanation:

You would add Shawn's hours of 5 with Ellie's of 7.

5+7=12

12/2=6

12 divided by 6 would give you the amount the Foreman suggested it would take them.