Working alone, machine X can manufacture 1,000 nails in 12 hours. Working together, machines X and Y can manufacture 1,000 nails in 6 hours. How many hours does it take machine Y to manufacture 1,000 nails working alone?
Select the correct option.
A) 3 9/17 B) 5 1/3 C) 7 D) 7 1/5 E) 12
rate of machine x = 1000/12   (1000/12 + y)6=1000   y=500/6=250/3   250/3 * t = 1000   t=12   E. 12
<result>E</result>
Working alone, machine X can manufacture 1,000 nails in 12 hours. Working together, machines X and Y can manufacture 1,000 nails in 6 hours. How many hours does it take machine Y to manufacture 1,000 nails working alone?