100 students appeared for two examinations. 60 passed the first, 0 passed the second and 30 passed both. Find the probability that a student selected at random has passed at least one examination.

Explanation

Given that no. of students who appeared for test =100


Let F be the event student passing first test

P(F)= probability that students pass the first test `=(60)/(100)​=3/5​`


Let S be the event student passing second test.

P(s): probability that students pass the second test
`=(50)/(100)​`


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