Pick the students
A class of 20 students has 14 students who study Math, 12 students who study physics and 2 students who study neither of them. If a student is picked out at random, the probability of that student studying both Math and Physics is a / b (in the simplest fraction form). What is a + b?
The answer is 7.
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1 solution
We draw a venn diagram and retrieve the equation:
14 - x + x + 12 - x + 2 = 20
which equals x = 8
Therefore, probability = 8 / 20, that means 2 / 5
Then, 2 + 5 = 7