A certain list consists of 21 different numbers.  If n is in the list and n is 4 times the average (arithmetic mean) of the other 20 numbers in the list, then n is what fraction of the sum of the 21 numbers in the list?

~$\frac{1}{20}$~

~$\frac{1}{6}$~

~$\frac{1}{5}$~

~$\frac{4}{21}$~

~$\frac{5}{21}$~