EX 3.11 number of individuals in a household

• Scenario:
  • Selecting a household in a certain region at random
  • Let $X$ = number of individuals in the selected household
• Given probability mass function (pmf) of $X$:
  • To be provided or determined

$X$	1	2	3	4	5	6	7	8	9	10
p(X)	.140	.175	.220	.260	.155	.025	.015	.005	.004	.001

• Consists of 1 million households
  • Each household has its own $X$ value
  • Proportion with each $X$ value is given by $p(x)$
• Alternative Viewpoint:
  • Forget about households
  • Consider the population as consisting of $X$ values
    • $14\%$ of values are $1$
    • $17.5\%$ are $2$
    • And so on…
• PMF Description:
  • Describes the distribution of possible population values $1,2,\dots ,10$