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A box contains 6 red marbles numbered 1 through 6 and 4 white marbles numbered from 12 through 15. Find the probability that a marble drawn is (i) white (ii) white and odd numbered (iii) even numbered (iv) red or even numbered. |
Answer» Given: box containing 6 red marbles numbered 1-6, 4 white marbles numbered 12-15. Formula: P(E) = \(\frac{favorable\ outcomes}{total\ possible\ outcomes}\) one marble is drawn from the given box, total possible outcomes are 10C1 therefore n(S)= 10C1 = 10 (i) let E be the event of getting white marble n(E)= 4C1 = 4 P(E) = \(\frac{n(E)}{n(S)}\) P(E) = \(\frac{4}{10}\) = \(\frac{2}{5}\) (ii) let E be the event of getting white marble with odd numbered E= {13,15} n(E)= 2 P(E) = \(\frac{n(E)}{n(S)}\) P(E) = \(\frac{2}{10}\) = \(\frac{1}{5}\) (iii) let E be the event of getting even numbered marble E= {2, 4, 6, 12, 24} n(E)= 5 P(E) = \(\frac{n(E)}{n(S)}\) P(E) = \(\frac{5}{10}\) = \(\frac{1}{2}\) (iv) let E1 be the event of getting red marble P(E1) = \(\frac{6}{10}\) (from(i)) Let E2 be the event of getting even numbered marble P(E2) = \(\frac{5}{10}\) (from (ii)) Therefore (E1ꓵ E2) = red coloured and even numbered n (E1 ꓵ E2) =3 P(E1ꓵ E2) = \(\frac{3}{10}\) By law of addition P(E1∪ E2) = P(E1) + P(E2) - P(E1 ꓵ E2) P(E1 U E2) = \(\frac{6}{10}+\frac{5}{10}-\frac{3}{10}=\frac{8}{10}=\frac{4}{5}\) |
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