In a binomial experiment with $n$ trials and a success probability of $p$, when can the distribution of $X$ be approximated by a normal distribution, and what are its mean and standard deviation?

When $n\ge 30$

$\mu =np(1-p)$

$\sigma =\sqrt{n}$

When $np\ge 10$, $n(1-p)\ge 10$

$\mu =np$

$\sigma =\sqrt{np(1-p)}$

When $p\ge 0.5$

$\mu =p$

$\sigma =\sqrt{p(1-p)}$

When $n(1-p)\le 5$

$\mu =n$

$\sigma =\sqrt{p}$