Truck A and Truck B move grain into a box at the rate of 20 kilos/min and 13 1/3 kilos a min respectively while truck C removes grain from the box at the rate of 10 kilos/min. If the capacity of the box is 2.4 tons, and Truck A, Truck B and Truck C are working simultaneously Then the box will be filled in?
a) 1 1/2 hrs
b) 3/5 hrs
c)1 5/7 hrs
d)2 1/8 hrs

• work done by all trucks in 1 min =(20+(40/3)-10)=70/3
  70/3 kilos is filled in one min..then 2400 kilos will be filled in..2400*(3/70)=720/7 mins= (12/7)*60 mins = 12/7 hrs
• 11 years agoHelpfull: Yes(11) No(1)
• total filled in i min=(20+40/3-10)=70/3
  to fill 70/3 time req-----=1min
  to fill 2400 time req-----=(3/70)*(2400/60)hr
  =1 5/7
• 11 years agoHelpfull: Yes(10) No(2)
• A fills 20 k/m
  B fills 40/3 k/m
  C removes 10 k/m = fills -10k/m
  total fills:= 20+40/3-10=70/3
  2.4ton= 2400 k
  so, 2400/(70/3)=720/7 min=12/7(60) min=12/7 hr
  
  12/7 hr= 1 5/7hr so ans is c.
  
• 11 years agoHelpfull: Yes(5) No(1)