if the probability that student a will fail a certain statis

if the probability that student a will fail a certain statistic examination is 0.5, the probability that student b will fail the examination is 0.2 and the probability that both student a and b will fail the examination is 0.1, what is the probability that at least one of these two students will fail the examination

Solution

Let

A , B = the events which A and B respectively fail

Hence,

P(A U B) = P(A) + P(B) - P(A n B)

= 0.5 + 0.2 - 0.1

= 0.6 [ANSWER]