day12.js

class Student extends Person {
    /*	
    *   Class Constructor
    *   
    *   @param firstName - A string denoting the Person's first name.
    *   @param lastName - A string denoting the Person's last name.
    *   @param id - An integer denoting the Person's ID number.
    *   @param scores - An array of integers denoting the Person's test scores.
    */
    // Write your constructor here

    /*	
    *   Method Name: calculate
    *   @return A character denoting the grade.
    */
    // Write your method here
    constructor(firstName, lastName, id, scores) {
        super(firstName, lastName, id);
        this.scores = scores

    };

    calculate() {
        let avg = this.scores.reduce((a, b) => a + b) / this.scores.length;
        if (avg >= 90 && avg <= 100) return "O";
        else if (avg >= 80 && avg < 90) return "E";
        else if (avg >= 70 && avg < 80) return "A";
        else if (avg >= 55 && avg < 70) return "P";
        else if (avg >= 40 && avg < 55) return "D";
        else return "T";
    }
}