To knwo the probability of something happening you just have to do the next equation, you take the total number of outcomes, and the total number of outcomes desired, and you divide the total number of outcomes desired by the number of outcomes possible.
Probability=
In this case you have a total of 30 marbles, thats the total number of outcomes possible.
And you have in the bag 7 black marbles that your number of outcomes desired.
C. The percentage of all homeowners that own at least one dog
Step-by-step explanation:
A parameter describes an entire population. Timothy is sampling from the 100 random homeowners to extrapolate their opinions onto the opinions of the entire population of homeowners.