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?  Pick one
A) 9
B) 10
C) 11
D) 12
E) 13
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= 
<gadget id="calculator">(3*2*8)/4</gadget>
<output>12</output>
12   correct answer(12)
<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?