Final answer:
Melissa needs to earn a 78 grade point average in her 4th quarter to raise her grade to a 3.0 cumulative grade point average.
Step-by-step explanation:
In order to calculate Melissa's 4th quarter grade point average needed to raise her cumulative grade point average to a 3.0, we need to find the average of all four quarters. Here's how you can do it:
- Add up her grade point averages for the first three quarters: 21 + 29 + 31 = 81.
- Next, we need to find out how much higher her 4th quarter grade point average needs to be to reach a cumulative average of 3.0. We can subtract the desired cumulative average from the sum of the first three quarters: 3.0 - 81 = -78.
- To find the grade point average for the fourth quarter, Melissa needs to earn a total of 78 points. Since there is only one grade left, we divide the required total by 1: 78 ÷ 1 = 78.
Therefore, Melissa needs to earn a 78 grade point average in her 4th quarter to raise her grade to a 3.0 cumulative grade point average.