A production tank filled with liquid buthanol for carbon

fiber prepreg is purged with krypton gas at a rate of $6$

kmo$\frac{l}{h}r\mathrm{.}40\%$mol buthanol vapor is present in the output

flow that exits the tank. Additionally, $3$kmo$\frac{l}{h}r$ of butane

gas enters this production tank. Please figure out how long

it will take for $20m3$ of liquid buthanol to evaporate. $50\%$

mol buthane is present in the output flow.