In a manufacturing plant, it takes 36 machines 4 hours of continuous work to fill 6 standard orders. At this rate, how many hours of continuous work by 72 machines are required to fill 12 standard orders?  Choose the correct choice from the following.
A) 4
B) 6
C) 8
D) 9
E) 12

Rationale: the choices give away the answer . . 36 machines take 4 hours to fill 8 standard orders . . in next eq we aredoubling the machines from 36 to 72 , but thework is not doubling ( only 1 1 / 2 times ) , = 4 * 48 / 72 * 12 / 6 = 4 ans a
Answer: A