The distribution of the number of schoolage children per fam

The distribution of the number of school-age children per family in the Whitehall Estates area of Boise, Idaho, is:

Determine the mean and standard deviation of the number of school-age children per family in Whitehall Estates. (Round your answers to 2 decimal places.)

A new school is planned in Whitehall Estates. An estimate of the number of school-age children is needed. There are 500 family units. How many children would you estimate?

Solution

(a)The mean is: 0*0.40+1*0.30+…+4*0.05=1.1

The standard deviation is:root over( 0^2*0.40+1^2*0.30+…+4^2*0.05-1.1^2)

=Root over(2-1.21)

=root over 0.79=0.88

(b) Some additional information is needed about only the families having children.

(c)X: 1      2        3        4

P(X):0.30   0.15    0.10   0.05