Thank you for pointing me in the direction of binomial distributions!

I think I figured out that in order for me to get the total probability for the household, I must use that formula for each member of the household, and add up the results. For instance, for a 3 person household my excel formula looks like:

=BINOMDIST(1,3,.65,FALSE) +

BINOMDIST(2,3,.65,FALSE) +

BINOMDIST(3,3,.65,FALSE)

(The format for the BINOMDIST formula in Excel is

**BINOMDIST**(**number_s**, **trials**, **probability_s**, **cumulative**)

Where number_s = the number of successes in trials,

trials = the number of independent trials,

Probability_s = probability of success,

Cumulative - When FALSE returns probability that there are number_s successes.)

This method returns these results for the given number of individuals in the household:

1 = .65

2 = .87

3 = .95

4 = .98

5 = .99

This "looks" right to me, but have I missed something? Thanks for your help.