Q27 of 43 Page 296

If the probabilities for A to fail in an examination is 0.2 and that for B is 0.3, then the probability that either A or B fails is

Let E1 be the event that A fails in an examination

and E2 be the event that B fails in an examination


Then, we have


P (E1) = 0.2 and P (E2) = 0.3


Now, we have to find the P (either E1 or E2 fails)


∴ P(either E1 or E2 fails) = P(E1) + P(E2) – P(E1⋂ E2)


≤ P(E1) + P(E2)


≤ 0.2 + 0.3


≤ 0.5


Hence, the correct option is (C)

More from this chapter

All 43 →
25

6 boys and 6 girls sit in a row at random. The probability that all the girls sit together is

 26

A single letter is selected at random from the word ‘PROBABILITY’. The probability that it is a vowel is

 28

The probability that at least one of the events A and B occurs is 0.6. If A and B occur simultaneously with probability 0.2, then P (bar a) + P (bar b) is

 29

If M and N are any two events, the probability that at least one of them occurs is