Probability - SS2 Mathematics Past Questions and Answers - page 1

\(probability\ of\ 3\ tails,\ P(TTT) = P(tail\ in\ 1st\ toss) + P(tail\ in\ 2nd\ toss) + P(tail\ in\ 3rd\ toss)\) (independent events)

\(P(TTT) = P(A \cap B \cap C) = P(A)P(B)P(C) = (\frac{1}{2})(\frac{1}{2})(\frac{1}{2}) = \frac{1}{8}\)

\[total\ number\ of\ english\ alphabets = 26\]

\[P(A) = \frac{5}{26}\]

\[P(B) = \frac{5}{26}\]

\(P(A\ or\ B) = P(A \cup B) = P(A) + P(B) = \ \frac{5}{26} + \frac{5}{26} = \frac{10}{26} = \frac{5}{13}\)

\[total\ number\ of\ balls = 6 + 4 + 5 = 15\]

\[P(r) = \ \frac{6}{15},\ \ P(b) = \ \frac{4}{15},\ \ P(g) = \ \frac{5}{15}\]

1. \(P(RED) = \frac{6}{15}\)

2. \(P(WHITE) = \frac{0}{15} = 0\)

3. \(P(BLUE) = \frac{4}{15}\)

4. \(P(not\ RED) = P(BLUE) + P(GREEN) = \ \frac{4}{15} + \frac{5}{15} = \frac{9}{15} = \frac{3}{5}\)

5. \(P(RED\ or\ WHITE) = P(RED) + P(WHITE) = \frac{6}{15} + 0 = \frac{6}{15}\)