Tell
At a certain high school, of the students took Physics, while took Chemistry, and of students took both.
If a student is selected at random, find the probability that he or she is in Physics or Chemistry, but not both.
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At a certain high school, 40% of the students took Physics, while 20% took Chemistry, and 5% of students took both.
So here we know that if a total of 40 percent of students took Physics, and 5 percent took Physics and chemistry, then 40-5 or 35 Percent of students took only physics.
Do the same with the chemistry group. (20-5) Percent.
Add the two together and you get 50 percent took, physics, chemistry, or both. So you have a 50/100 or a 50 percent Chance or selecting someone who is in Physics or Chemistry, but not both.