Eddie's average after four tests is 78%. He believes that if he scores 82% on his fifth test, his new average will be 80%. We need to determine if Eddie is correct and, if not, calculate the correct average.

1. Problem Description

Eddie's average after four tests is 78%. He believes that if he scores 82% on his fifth test, his new average will be 80%. We need to determine if Eddie is correct and, if not, calculate the correct average.

2. Solution Steps

First, we need to find the sum of Eddie's scores on the first four tests. We know that the average is calculated by dividing the sum of the scores by the number of scores. In this case:

$Average = \frac{Sum}{Number of tests}$

We know the average is 78% and the number of tests is

4. Therefore:

$78 = \frac{Sum}{4}$

$Sum = 78 \times 4$

$Sum = 312$

Next, we need to add the score of the fifth test (82%) to the sum of the first four tests:

$New Sum = 312 + 82$

$New Sum = 394$

Now, we calculate the new average by dividing the new sum by the new number of tests, which is 5:

$New Average = \frac{394}{5}$

$New Average = 78.8$

Therefore, Eddie's new average will be 78.8%, not 80%.

3. Final Answer

Eddie is incorrect. The correct average is 78.8%.