Final answer:
The probability that your bid of $21,000 will be accepted is 20%, since this is the proportion of the possible range of bids ($20,000 to $25,000) that falls below your bid.
Step-by-step explanation:
To calculate the probability that your bid will be accepted when you bid $21,000, we need to consider the range of possible bids from the other competitor, which is from $20,000 to $25,000. Since the competitor's bid is uniformly distributed, this means that all bids within this range are equally likely.
Because any bid over $20,000 can win and your bid is $21,000, the losing range for the competitor's bid, where you would win, is from $20,000 to just under $21,000. The length of this range is $21,000 - $20,000 = $1,000. The entire possible range for the competitor's bid is $25,000 - $20,000 = $5,000.
The probability that the competitor's bid is less than your bid of $21,000 is therefore the length of the winning range ($1,000) divided by the entire range ($5,000), which yields a probability of $1,000 / $5,000 = 0.2 or 20%.