Conditional probability, overlapping events and reverse reasoning

Answer: 154​

1. Among the 15 students who cycle, 4 are in Group A.
2. Probability =154​.

Answer: 2923​

1. Count the overlap once: 15+15−7=23.
2. Probability =2923​.

Answer: 72​

1. Each bag is equally likely and has 6 counters.
2. Of the 7 equally likely red outcomes, 2 come from Bag A:72​.