One bag contain 3 blue and 5 red balls, another bag contain 2 blue and 4 red balls respectively. One ball is…

Analyze the question: There are two bags. We draw one ball from each, and we want the probability that both are blue. The two draws are independent because they come from different bags.

Concept: For independent events, P(A and B) = P(A) × P(B).

Solution:

• Bag 1 has 3 blue and 5 red balls, which is 8 balls in total. P(blue from bag 1) = 3/8
• Bag 2 has 2 blue and 4 red balls, which is 6 balls in total. P(blue from bag 2) = 2/6 = 1/3

P(both blue) = 3/8 × 1/3 = 3/24 = 1/8

Checking the options:

• A: 2/15 ≈ 0.133, not equal to 0.125
• B: 3/24 = 1/8 = 0.125, which matches
• C: 3/21 = 1/7, no
• D: 3/28, no

Tip: When a question says "and" with separate bags (or separate events that don't affect each other), multiply the probabilities. Don't simplify too early. Here, 3/24 matches the option exactly, so keep your fractions in the form the options use. Also, check that you've used each bag's own total (8 for the first, 6 for the second) and not added the balls together.