Question 1098908
.
<pre>
20 minutes to fill 29*20 = 400 liters,


and then  additional  {{{(4000-400)/(20-2)}}} = {{{3600/18}}} = 200 minutes

to fill the remaining  4000-400 = 3600 liters at the rate of (20-2) = 18 liters per minute.


In total, 220 minutes, or 3 hour 40 minutes.
</pre>