PHP Puzzles: Grade Deviations

We’re continuing with grades and statistics by calculating statistics for Grade Point Averages. In the educational system in the United States, it’s a way to boil down the grades across the multiple courses taken by a student. It involves translating a letter grade back to a numeric value and then calculating a weighted average. At the end of all this, we’re left with a singular number we can use for a rough comparison between students.