viarno reshenie exam

function exam(input) {
    let index = 0;
    let numbersOfStudents = Number(input[index]);
    index++;
    let numberOfFailedStudents = 0;
    let numberOfAverageStudents = 0;
    let numberOfGoodStudents = 0;
    let numberOfExcellentStudents = 0;
    let totalResult = 0;

    for (let i = 1; i <= numbersOfStudents; i++) {  // '<=' instead of '<' ????????????????
        let grade = Number(input[i]);  // Number(...)
        totalResult += grade;

        if (grade <= 2.99) {
            numberOfFailedStudents++;
        } else if (grade >= 3.00 && grade <= 3.99) {
            numberOfAverageStudents++;
        } else if (grade >= 4.00 && grade <= 4.99) {
            numberOfGoodStudents++;
        } else if (grade >= 5.00) {
            numberOfExcellentStudents++;
        }
    }
    let percentnumberOfFailedStudents = numberOfFailedStudents / numbersOfStudents * 100;
    let percentnumberOfAverageStudents = numberOfAverageStudents / numbersOfStudents * 100;
    let percentnumberOfGoodStudents = numberOfGoodStudents / numbersOfStudents * 100;
    let percentnumberOfExcellentStudents = numberOfExcellentStudents / numbersOfStudents * 100;

    // console.log(`Top students: ${percentnumberOfFailedStudents.toFixed(2)}%`);  // Error!
    console.log(`Top students: ${percentnumberOfExcellentStudents.toFixed(2)}%`);
    // console.log(`Between 4.00 and 4.99: ${percentnumberOfAverageStudents.toFixed(2)}%`);
    console.log(`Between 4.00 and 4.99: ${percentnumberOfGoodStudents.toFixed(2)}%`);
    // console.log(`Between 3.00 and 3.99: ${percentnumberOfGoodStudents.toFixed(2)}%`);
    console.log(`Between 3.00 and 3.99: ${percentnumberOfAverageStudents.toFixed(2)}%`);
    // console.log(`Fail: ${percentnumberOfExcellentStudents.toFixed(2)}%`);
    console.log(`Fail: ${percentnumberOfFailedStudents.toFixed(2)}%`);

    let average = Number(totalResult / numbersOfStudents);
    console.log(`Average: ${average.toFixed(2)}`);
}

exam(['6', '2', '3', '4', '5', '6', '2.2']) ;