Question 760720
An 80 gallon tank is being filled with water by two pipes. One pipe fills the tank at 6 gallons per second. The second pipe fills the tank at 5 gallons per second. After 5 seconds, pipe one clogs and is now filling the tank at 2 gallons per second. How long will it take for the 80 gallon tank to be filled?
***
let x=time it will take to fill 80 gal tank
1/6=flow-rate of pipe one for 5 sec
1/2=flow-rate of pipe one for (x-5) sec
1/5=flow-rate of pipe two for (x) sec
volume=flow-rate*time
..
{{{5/6+(x-5)/2+x/5=80}}}
LCD:30
{{{25+15x-75+6x=2400}}}
21x=2450
x≈116.67
time it will take to fill 80 gal tank≈116.67sec