Amachine can label 339 jars in 3 hours. if the rate of the machine was doubled, how many jars would be labeled in 11 hours at the new rate?

339/3=113.

therefore the original rate is 113 labels/hour.

If this was doubled, the new rate would be 226 labels/hour.

In eleven hours there would be 226x11=2486

2486 jars would be labelled.

You could do this in quite a few different ways. 

12 feet because you take 10 feet and multiply by 12 to make it inches then divide that by 15 to find the scale factor and it is 8 so you take 18 and multiple that by 8. You get 144. You then divide that by 12 to convert it back to feet and you get 12 feet.