ANSWER ASAP PLEASE

An apartment building has nine floors and each floor has four apartments. The building owner wants to install
new carpeting in eight apartments to see how well it wears before she decides whether to replace the carpet in
the entire building.
The figure below shows the floors of apartments in the building with their apartment numbers. Only the
nine apartments indicated with an asterisk (*) have children in the apartment.

(a) For convenience, the apartment building owner wants to use a cluster sampling method, in which the floors
are clusters, to select the eight apartments. Describe a process for randomly selecting eight different
apartments using this method.
(b) An alternative sampling method would be to select a stratified random sample of eight apartments, where the
strata are apartments with children and apartments with no children. A stratified random sample of size eight
might include two randomly selected apartments with children and six randomly selected apartments with no
children. In the context of this situation, give one statistical advantage of selecting such a stratified sample as
opposed to a cluster sample of eight apartments using the floors as clusters.