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

1. First, we find the total sum of the 15 numbers. We know the average is 21, so we multiply 21 by 15 to get 315.

2. Next, we find the sum of the first 10 numbers. We know their average is 15, so we multiply 15 by 10 to get 150.

3. Then, we find the sum of the last 6 numbers. We know their average is 25, so we multiply 25 by 6 to get 150.

4. Now, we know that the 10th number is counted in both the first 10 numbers and the last 6 numbers. So, to find the 10th number, we add the sum of the first 10 numbers and the sum of the last 6 numbers, then subtract the total sum of the 15 numbers. That is, (150 + 150) - 315 = -15.

5. However, a number cannot be negative in this context, so we take the absolute value of -15, which is 15.

So, the 10th number is 15.

Question

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

1. First, we find the total sum of the 15 numbers. We know the average is 21, so we multiply 21 by 15 to get 315.

2. Next, we find the sum of the first 10 numbers. We know their average is 15, so we multiply 15 by 10 to get 150.

3. Then, we find the sum of the last 6 numbers. We know their average is 25, so we multiply 25 by 6 to get 150.

4. Now, we know that the 10th number is counted in both the first 10 numbers and the last 6 numbers. So, to find the 10th number, we add the sum of the first 10 numbers and the sum of the last 6 numbers, then subtract the total sum of the 15 numbers. That is, (150 + 150) - 315 = -15.

5. However, a number cannot be negative in this context, so we take the absolute value of -15, which is 15.

So, the 10th number is 15.

Knowee AI · Accepted Answer

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

1. First, we find the total sum of the 15 numbers. We know the average is 21, so we multiply 21 by 15 to get 315.

2. Next, we find the sum of the first 10 numbers. We know their average is 15, so we multiply 15 by 10 to get 150.

3. Then, we find the sum of the last 6 numbers. We know their average is 25, so we multiply 25 by 6 to get 150.

4. Now, we know that the 10th number is counted in both the first 10 numbers and the last 6 numbers. So, to find the 10th number, we add the sum of the first 10 numbers and the sum of the last 6 numbers, then subtract the total sum of the 15 numbers. That is, (150 + 150) - 315 = -15.

5. However, a number cannot be negative in this context, so we take the absolute value of -15, which is 15.

So, the 10th number is 15.

The average of 15 numbers is 21. If the average of the first 10 numbers is 15 and the average of the last 6 numbers is 25, what is the 10th number? Options 25 15 10 20

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