Navigator, I think you need to read my last post and the few preceding it again.
I did not suggest that a battery would have an internal resistance of 24 ohm. I actually argued that this is an unrealistic figure.
If you look at the posts from tolipanebas, you will see that it is he who suggested a 24 ohm internal resistance. Indeed his entire argument was based upon that assumption.
You are also correct that no load is specified. But my original estimate of a load of 12 ohms was in response to toilpanebas's assumption that the current was 1 amp.
To summarise my comments:
The question is flawed in that its asks for the life of a 24 ampere hour battery but does not indicate what current is flowing.
The assumption by tolipanebas that the batteries have a 24 ohm resistnace and that this is the only resistance in the circuit, is unfounded.
If tolipanebas is correct however, then when the batteries are connected and a current flows the voltage measured across the terminal will be zero.
I think you will find that my electrical theory is quite sound but you need to read the entire string to following the arguments.