a public health org reports that 28 of bab boys 68 months ol

a public health org reports that 28% of bab boys 6-8 months old in us weigh more than 20 pounds. a sample of 14 babies is studied. what is the standard deviation of the number who weigh more than 20 pounds in a sample of 14 babies aged 6-8 months.    round answer to four decimal places

Solution

1ST WE WILL CALULATE THE VARIANCE THEN WE WILL TAKE THE SQUARE ROOT OF THAT AND WE WILL GET THE STANDARD DEVIATION

NOW VAR (X) = E(X^2) - E(X)^2

14 SAMPLE

E(X) = 14*0.28 = 3.92

E(X)^2= 15.36

E(X^2) = 54.88

VAR(X) = 54.88 - 16.36 = 39.52

STANDARD DEV = 39.52^(1/2) = 6.2864