(i) The probability that the person chosen is from country A is given by the ratio of the number of people in country A to the total number of people:

\(P(A) = \frac{3}{15} = 0.2\)

(ii) To find the probability that the person chosen does not have sugar in their tea, we calculate the probabilities for both countries and sum them:

In country A, 70% do not have sugar: \(0.7 \times 3 \text{ million} = 2.1 \text{ million}\)

In country B, 35% do not have sugar: \(0.35 \times 12 \text{ million} = 4.2 \text{ million}\)

Total without sugar: \(2.1 + 4.2 = 6.3 \text{ million}\)

Probability: \(P(\text{not S}) = \frac{6.3}{15} = 0.42\)

(iii) Given that the person does not have sugar, the probability they are from country B is:

\(P(B | \text{not S}) = \frac{0.8 \times 0.35}{0.42} = 0.667\)