To calculate the probability of each event, we use the formula for probability: probability = number of desired outcomes / number of total outcomes. For event A, we have 9 nickels and need to choose 2 without replacement. The number of ways to choose 2 nickels is (9 choose 2) = 36. The total number of ways to choose any 2 coins from 18 coins is (18 choose 2) = 153. Thus, the probability is 36/153 = 0.23529411764705882. For event B, since we are replacing the coin after the first draw, the probability of choosing a nickel first is 9/18 and then a dime is 3/18, giving us (9/18) * (3/18) = 0.08333333333333333. For event C, without replacement, the probability of choosing a nickel first is 9/18 and then a dime is 3/17, resulting in (9/18) * (3/17) = 0.08823529411764706. For event D, we first choose a penny (6/18), then 2 nickels without replacement, which is (9/17) * (8/16), leading to (6/18) * (9/17) * (8/16) = 0.08823529411764705.