WAEC Mathematics 2023 Paper

Concept:The only common colour in both bags is blue, so both picked marbles must be blue.Explanation:First bag has 4 white and 3 blue marbles, giving a total of 7 marbles.Probability of drawing a blue marble from the first bag = $\frac{3}{7}$.Second bag has 5 red and 6 blue marbles, giving a total of 11 marbles.Probability of drawing a blue marble from the second bag = $\frac{6}{11}$.Since the two draws are independent, multiply the probabilities:$\frac{3}{7} \times \frac{6}{11} = \frac{18}{77}$.White marbles exist only in the first bag and red marbles only in the second bag, so no other same-colour outcome is possible.Answer:$\frac{18}{77}$, which is option B.