three taps fills water in a tank.one fills it in 3hrs another in 4hrs and the third in 6hrs.if all run together how soon will they fill the tank?
their rates of filling would be
1/3 , 1/4, and 1/6
combined rate = 1/3 + 1/4 + 1/6
= 3/4
time at combined rate
= 1/(3/4)
= 4/3
It would take 4/3 hrs, or 1 hour and 20 minutes