Question

Weighted average standard deviation of binomial infection model

The weighted average is np.

The weighted average standard deviation is sqrt(np(1-p))

Please help!!

Answer 1

In general, the distribution of a binomial random variable may be
accurately approximated by that of a normal random variable,
as long as np ≥ 5, nq ≥ 5, and assuming that a continuity correctionî is made to account for the fact that we are using a
continuous distribution (the normal) to approximate a discrete one
(the binomial).
For approximating the distribution of X, we will use the
normal distribution with mean = np, variance = npq

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