A bag contains 3 red and 4 black balls. Two balls are drawn at random. What is the probability that both are black?
Q1. A bag contains 3 red and 4 black balls. Two balls are drawn at random. What is the probability that both are black?
Answer: 2 / 7
Explanation: Total balls = 7, ways to draw 2 balls = 7C2 = 21. Ways to draw 2 black balls = 4C2 = 6. Probability = 6 / 21 = 2 / 7.