Answer: 1/4.
Explanation:
The probability of selecting a nickel first and then a dime is calculated as follows:
Step 1: Determine the number of successful outcomes. There are 4 nickels and 9 dimes in the bag, so there are 4 successful outcomes of selecting a nickel first.
Step 2: Determine the number of possible outcomes. Since David is selecting 2 coins from the bag one at a time without replacement, the number of possible outcomes is 16 (9 + 4 + 3).
Step 3: Calculate the probability. The probability of selecting a nickel first and then a dime is 4/16 = 1/4.
So, the probability that David will select a nickel first and then a dime is 1/4.