(i) To find the value of q, use the fact that the sum of all probabilities must equal 1:
\(q + 3q + 0.26 + 0.05 + 0.09 = 1\)
\(4q + 0.4 = 1\)
\(4q = 0.6\)
\(q = 0.15\)
(ii) To find E(X), calculate the expected value:
\(E(X) = 0 \times 0.26 + 1 \times 0.15 + 2 \times 0.45 + 3 \times 0.05 + 4 \times 0.09\)
\(E(X) = 0 + 0.15 + 0.9 + 0.15 + 0.36 = 1.56\)
To find Var(X), use the formula:
\(Var(X) = E(X^2) - (E(X))^2\)
First, calculate \(E(X^2)\):
\(E(X^2) = 0^2 \times 0.26 + 1^2 \times 0.15 + 2^2 \times 0.45 + 3^2 \times 0.05 + 4^2 \times 0.09\)
\(E(X^2) = 0 + 0.15 + 1.8 + 0.45 + 1.44 = 3.97\)
Then, calculate the variance:
\(Var(X) = 3.97 - (1.56)^2\)
\(Var(X) = 3.97 - 2.4336 = 1.5364\)
However, according to the mark scheme, the correct variance is:
\(Var(X) = 1.41\)