Here u go
dv/dt=1600
emptying given in dh/dt=k rooth
so in this case the rate at which the height of the cylinder increases would be given by
h=1600/4000(area of cross-section)- kroot h
dh/dt= 0.4-krooth
when u take rate=400cm3
h=400/4000=0.1 since h=25
0.1=5k
k=0.02
If you can check the ms for the last 2 ans...im not sur abt mine.....