3 pumps, working 8 hours a day, can empty a tank in 2 days. how many hours a day must 4 pumps work to empty the tank in 1 day? Choose the correct choice from the following answers:  A) 9  B) 10  C) 11  D) 12  E) 13
<gadget id="calculator">3 * 8</gadget>
<output>24</output>

<gadget id="calculator">24 * 2</gadget>
<output>48</output>

<gadget id="calculator">48 / 4</gadget>
<output>12</output>

<result>D</result>
3 pumps, working 8 hours a day, can empty a tank in 2 days. how many hours a day must 4 pumps work to empty the tank in 1 day?
divide(multiply(multiply(3, 8), 2), 4)
the required number of working hours per day x , more pumps , less working hours per day ( indirect ) less days , more working hours per day ( indirect ) pumps 4 : 3 , days 1 : 2 } : : 8 : x therefore 4 * 1 * x = 3 * 2 * 8 , x = ( 3 * 2 * 8 ) / 4 x = 12 correct answer ( d )