Suppose that a city has 90000 dwelling units, of which 35000 are houses, 45000 are apartments, and 10000 are condominiums. We want to estimate the overall proportion (p) of households in which energy conservation is practiced, with a bound on the error of estimation equal 0.1.

Q: Find the strata sample sizes for houses, apartments, and condominiums, n₁,n₂, and n₃, and the sample size n.