A shopping center includes a grocery store and a drug store. One afternoon, a total of 200 people visited the shopping center,
and 121 shopped at the grocery store, 91 shopped at the drug store, and 33 shopped at both businesses. a) How many people shopped at the grocery store or the drug store? b) How many people shopped at neither the grocery store nor the drug store?
When making a Venn diagram for a problem like this, it often works well to fill in the "both" quantity first. Then that is subtracted from the number for grocery to find "grocery only", and from the number for drug store to find "drug store only." The sum of the numbers inside the circles (88+33+58) is the number who shopped at the grocery or drug store. The number who shopped at neither is the difference between this number and the total number of shoppers (200-179).