답안

let student_score = [];
let class_score = [];
let total_score = [];

for (let k = 0; k < 7; k++) {
  class_score = [];
  for (let j = 0; j < 30; j++) {
    student_score = [];
    for (let i = 0; i < 5; i++) {
      student_score.push(Math.floor(Math.random() * 100) + 1);
    }
    class_score.push(student_score);
  }
  total_score.push(class_score);
}

console.log(total_score);

let total_average = [];
let c_average = [];
let s_average = 0;
let s_sum = 0;
let c_sum = 0;
let student_one = 0;
let 일등 = 0;

for (let c of total_score) {
  // console.log(c);
  for (let s of c) {
    s_sum = s.reduce((a, b) => a + b);
    s_average = s_sum / 5;
    c_average.push(s_average);
    if (일등 < s_average){
      일등 = s_average;
    }
  }
  console.log(일등);
  일등 = 0;
  console.log(c_average);
  total_average.push(c_average.reduce((a, b) => a + b)/30);
  c_average = [];
}
console.log(total_average);
console.log(total_average.reduce((a, b) => a + b)/7);