Running at the same constant rate,6 identical machines can produce a total of 270 bottles per minute.At this rate,how many bottles could 12 such machines produce in 4 minutes ?
Pick one.
A) 648	B) 1800	C) 2700	D) 2160	E) none of these

Rationale: "solution let the required number of bottles be x . more machines , more bottles ( direct proportion ) more minutes , more bottles ( direct proportion ) â ˆ ´ 6 ã — 1 ã — x = 12 ã — 4 ã — 270 â ‡ ” x = 12 x 4 x 270 / 6 = 2160 . answer d"
Answer: D