Can you help with the standard deviation (b) for this problem? I have answered part a below.

According to the Massachusetts Department of Health, 224 women who gave birth in the state of Massachusetts in 1988 tested positive for the HIV antibody. Assume that, in time, 25% of the babies born to such mothers will also become HIV-positive.

(a)I fsamples o f size 224 were repeatedly selected from the population o f chil-dren born to mothers with the HIV antibody, what would be the mean numberof infected children per sample?

The mean number of infected children per sample is 56.

u=np

=224 x 0.25

=56

(b)What would be the standard deviation?