A town has two shopping malls. A survey conducted on the shopping preferences of the town's residents showed that 62% of the residents visit Comet Mall, 73% of the residents visit Star Mall, and 48% of the residents visit both malls.
The probability that a resident chosen at random shops at either Comet Mall or at Star Mall is
%.

Question

A town has two shopping malls. A survey conducted on the shopping preferences of the town's residents showed that 62% of the residents visit Comet Mall, 73% of the residents visit Star Mall, and 48% of the residents visit both malls.
The probability that a resident chosen at random shops at either Comet Mall or at Star Mall is 
%.

Mercury · Answer

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venn diagram of the situation

notice how "62% of residents visit comet mall" includes the people who *only* visit comet mall, as well as the people who visit both

therefore, if we want to know what % of people *only* visit comet mall, we can simply subtract 62% - 48%

same logic with the % of people who only visit star mall

now, to find the "The probability that a resident chosen at random shops at either Comet Mall or at Star Mall" we need to add:

1. the people who only visit comet mall
2. the people who only visit star mall
3. the people who visit both