Manhattan - Word Translations - 4th edition - Issue!

[orlando.agostinho]

Hi, Guys!

First, thanks for your great job!

Well, i have one doubt about ratio problems: Page 60, problem #13:

It said that the Machine A -lowest one- did the work in 6 hours. BUT, I don't get it why!

Machines A,B e C work together along 3 hours. At the beginning 4th four, the Machine A, stopped. After, at the beginning, the 7th hour, began again to work until 9th hours. For me, Machine A, worked only 5 hours and not 6 hours.

Please, can you help me?

Thanks!
Cheers!

[Ben Ku]

You can think of this in terms of time.

12:00 - All three machines work together.
3:00 (end of hour 3; beginning of hour 4)- Machine A stops, only Machines B and C work
6:00 (end of hour 6; beginning of hour 7) - All three machines work together
9:00 - work is done.

So Machine A works from 12:00 to 3:00 (3 hours), and then from 6:00 to 9:00 (3 hours).

Hope that helps.