Table below haves the distribution of the size of households (limited to 4 people).
|
Inhabitants
|
1
|
2
|
3
|
4
|
|
Proportion of households
|
0.4
|
0.3
|
0.1
|
0.2
|
a) Determine the average size of the household
b) Determine the variance of the size of the household
c) Determine the probability that a randomly chosen household consists of no more than 3 inhabitants