The health department physician in a suburban community warned cat owners about a risk of infection. Cats leave their litter boxes and then jump on counters, trailing bacteria behind them. To highlight the greater risk to the health of cat owners than dog owners, the physician went to the homes of cat owners and dog owners, swabbed kitchen counters, cultured the swabs, and counted the number of bacteria that grew. She planned to use a t test to compare the mean number of bacteria in cat-owning households versus dog-owning houses.

(a) Write out H₀ and H₁ and

(b) Explain what they mean.