Chapter 8 - Section 8.5 - Inclusion-Exclusion - Exercises - Page 557: 3

1%

Let $A$ denote the set of households that have at least one television set, and $B$ denote the set of households that have telephone service. It is given that $|A|=96\%$, $|B|=98\%$, and $|A\cup B|=95\%$. By the Principle of Inclusion-Exclusion, $|A\cup B|=|A|+|B|-|A\cap B|=96\%+98\%-95\%=99\%$. We are looking for the percentage of households with neither telephone service nor at least one television set, which is $100\%-|A\cup B|-100\%-99\%=1\%$.