Five machines at a certain factory operate at the same constant rate. If four of these machines, operating simultaneously, take 40 hours to fill a certain production order, how many fewer hours does it take all five machines, operating simultaneously, to fill the same production order?
Choose the correct choice from the following.
A) 3	B) 5	C) 6	D) 8	E) 24
Total work = 4*40 machine hrs   Time taken = 4* 40 /5= 
<gadget id="calculator">4* 40 /5</gadget>
<output>32</output>
&gt; 32 hours...   Thus all five machines, operating simultaneously will take ( 40 - 32 ) 8 hours..   Answer will be (8) 8
<result>D</result>
Five machines at a certain factory operate at the same constant rate. If four of these machines, operating simultaneously, take 40 hours to fill a certain production order, how many fewer hours does it take all five machines, operating simultaneously, to fill the same production order?