Question 176622: 4. Consider the following contingency table:
Under 20 21-30 31-40
Male 12 12 17
Female 13 16 21
a. If one person is selected at random, what is the probability that person is Female? ______
b. If one person is selected at random, what is the probability that person is either under 20 or over 30? _______
c. If one person is selected at random, what is the probability that person is either male or in the age group 21-30? _____
d. If two people are selected at random, what is the probability they are both female? ______
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website! First thing you need is the total number of people, call that  .
There are six entries in the table, so just add them to get
For the first three problems, just add up the number of people who fit into the given category and then divide by the value you calculated for . For problem a, for example, 41 of the people are male, so the probability is  .
For the last problem, you need the probablility that the first person will be a female, namely  times the probability that the second person will be a female as well considering that the pool of people is one smaller, and the pool of available females is also one smaller, so  .
Write back if you are still having trouble.
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