Question 574530
2. One pipe can fill a tank in 4 hours. Together with a second pipe, the tank can be filled in 3 hours. How long would it take the second pipe alone to fill the tank??
SO I WILL SOLVE ONLY THE SECOND PART
sol:
 work done by second pipe = work done by both pipes - work done by one pipe  
                          =( 1/3 ) - (1/4)
                          = 1/12
so second pipe can fill the tank by 12 hours.