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Introduction to Contional Probability.
1. A family has two children. What is the probability that both the children are girls given that at least one of them is girl?
2. One card is drawn randomly from ten cards numbered 1 to 10. If it is known that the number on the drawn card is more then 3, what is the probability that it is an even number?
3. David has a question bank consisting of 300 easy type X, 200 difficult type X, 500 easy type Y and 400 difficult type Y questions. If a auestion is selected at random from the question bank, what is the probability that it will be an easy question given that it is a type Y question?