The average of 25 results is 18. The average of first 12 of those is 14 and the average of last 12 is 17. What is the 13th result?

To solve this problem, we need to use the formula for the average, which is the sum of the numbers divided by the count of the numbers.

1. First, we find the total sum of all 25 results. Since the average is 18, we multiply 18 by 25 to get 450.

2. Next, we find the total sum of the first 12 results. Since their average is 14, we multiply 14 by 12 to get 168.

3. Then, we find the total sum of the last 12 results. Since their average is 17, we multiply 17 by 12 to get 204.

4. Now, we know that the 13th result is included in both the first 12 and the last 12 results. So, to find the 13th result, we add the total of the first 12 results and the total of the last 12 results, then subtract the total of all 25 results.

So, the 13th result is 168 + 204 - 450 = -78.

However, a negative result doesn't make sense in this context. This could be due to a mistake in the problem's setup. Please check the numbers and try again.