Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is:
Answers
A) 60 gallons  B) 100 gallons  C) 120 gallons  D) 180 gallons  E) 80 gallons
Let the capacity of tank x gallons. then in 1 minute tank filled (x/20+x/24-3)gallons   From the question we can write   15(x/20+x/24-3)=x [it took 15 min to fill x gallons]   x/20+x/24-x/15=3   (6x+5x-8x)/120=3   3x/120=3   x=120 gallons   ANSWER :120 gallons
<result>C</result>
Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is: