* 9th grade: GPA_9 = 3.27
* 10th grade: GPA_10 = 3.47
* 11th grade: GPA_11 = 4.28
* 12th grade: GPA_12 (this is what we need to find)
To calculate the overall GPA, we need to consider the weighting of each grade. Assuming each grade carries equal weight, we can average the GPAs:
Overall GPA = (GPA_9 + GPA_10 + GPA_11 + GPA_12) / 4
We want the overall GPA to be 4.0, so we can set up the equation:
4.0 = (3.27 + 3.47 + 4.28 + GPA_12) / 4
Now, let's solve for GPA_12:
4.0 * 4 = 3.27 + 3.47 + 4.28 + GPA_12
16 = 11.02 + GPA_12
GPA_12 = 16 - 11.02
GPA_12 = 4.98
Therefore, you would need a 4.98 GPA in 12th grade to achieve a 4.0 overall GPA. However, since a GPA above 4.0 is generally not possible (unless there's a weighted grading system with extra credit opportunities), achieving a perfect 4.0 overall GPA is not attainable with these previous grades.