Question

1. The probability that it will be a sunny day is 0.4. Find the expected number of fine days in a week and also the standard deviation.

Answer 1

$\mu=np=7*0.4=2.8.$

$\sigma=\sqrt{np(1-p)}=\sqrt{7*0.4*0.6}=\sqrt{1.68}\approx1.2961.$