<PRE><B>Question 449997</B>
a cooling tank can be filled by 1 pipe in 24 mins. and by the another pipe in 30 mins.how long will it takes to fill the tank if both pipes are used at the same time..?? 
-------------------
1st pipe rate = 1/24 job/min
2nd pipe rate = 1/30 job/min
-----
Together rate = 1/x job/min
----
Equation:
1/24 + 1/30 = 1/x
---
30x + 24x = 24*30
54x = 720
--
x = 13 1/3 minutes (time to do the job together)
=======================================================
Cheers,
Stan H.</PRE>