We are told that there are two types of material for the kitchen countertops and three types of kitchen floor. With this information, we can draw the following area diagram.
From the exercise, we know that 20 % of the homes used granite while 80 % used porcelain. We also know that of the 45 homes, 15 used red oak, 20 used white oak, and 10 used maple. Let's add this information to the diagram.
We are interested in knowing the probability of getting red or white oak with a granite kitchen countertop. To do that, we have to multiply the probabilities of these events. For this purpose, we will rewrite the percentages describing the homes with kitchen countertops as fractions.
20 % = 1/5 and 80 % = 4/5
With this information, we can calculate the probability of a home having either type of oak floor and granite countertops by multiplying the probabilities. To simplify the calculations, we will reduce the fraction along the horizontal axis of the area diagram to their simplest forms.
By adding the probabilities in the diagram, we get the total probability of getting an oak floor with granite countertops.
3/45+4/45=7/45≈ 15.6 %
