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 10 such machines produce in 4 minutes ?  Choose the correct choice from the following options.
A) 648 B) 1800 C) 2700 D) 10800 E) None of these
Solution   Let the required number of bottles be x.   More machines,More bottles (Direct Proportion)   More minutes,More bottles (Direct Proportion)   ∴ 6 × 1 × x = 10 × 4 × 270 ⇔ x = 10x4x270/6= 1800 . Answer 1800
<result>B</result>
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 10 such machines produce in 4 minutes ?