Two cards are drawn successively with replacement from a well shuffled deck of 52 cards, then the mean of the number of aces is

$\frac{2}{13}$

Let X denote the number of aces obtained in two draws. Then, X follows binomial distribution with n=2, $p=\frac{4}{52}=\frac{1}{13}$ and $q = \frac{12}{13}$

∴ Mean of number of aces $= np = \frac{2}{13}.$