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One ticket is drawn at random from a bag containing 20 tickets numbered 1 to 20. Find the probability that it is a multiple of 2 or 5, |
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Answer» Since the bag has 20 tickets, total number of cases n = 20 Let A: getting a multiple of 2 B: getting a multiple of 5 Event A has 10 favourable outcomes A = {2, 4, 6, 8, 10, 12, 14, 16, 18, 20} ∴ P(A) = \(\frac{10}{20} =\frac{1}{2}\) Event B has four favourable outcomes B = {5, 10, 15, 20) ∴ P(B) = \(\frac{4}{20}\) A ∩ B = {10,20] ∴ P(A ∩ B) = \(\frac{2}{20}\) ∴ P(multiple of 2 or 5 ) = P(A ∪ B) =P(A) + P(B) – P(A ∩ B) = \(\frac{10}{20} + \frac{4}{20} - \frac{2}{20} = \frac{12}{20} = \frac{3}{5}\) |
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