Example #2
A recent survey of 100 college students asked if they prefer to drink tea, coffee, or an energy drink during finals week. Here is the table created from that survey.
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Let's look at a couple questions you could see on a test.
How many college students drink tea given that they are a female? In this question, we're looking for tea drinkers that are female. Let's look at the female row and tea column. The answer is 18.
How many students drink tea or are male? In this question, we're looking for all tea drinkers united with all males. To figure out the answer, let's highlight the Tea column and Male row. We do have an overlap at Tea and Male, so be sure not to add that twice. So our answer is Total Tea drinkers 20 plus Total Males 56
minus the overlap of 2. 20 + 56 - 2 = 74. There are 74 students that are tea drinkers or male.
How many coffee or tea drinkers are not female? Let's look at each part. Let's highlight the coffee and tea columns. Now, let's highlight the male row. Remember, the question asks for drinkers that are not female, so they have to be male.
So our answer will unite the coffee and tea drinkers with the contingency that they are males. Males that drink tea are 2, males that drink coffee, 15. 2 + 15 = 17. There are 17 males that drink coffee or tea.