第一版
using System;

namespace homework5
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("請輸入班級人數");
            int peopleNum = int.Parse(Console.ReadLine());
            double[] score = new double[peopleNum];

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine("請輸入第" + (i+1) + "位同學的成績");
                score[i] = double.Parse(Console.ReadLine());
            }


            Console.WriteLine("編號\t\t成績");  // \t可以水平定位
            Console.WriteLine("--------------------");

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine((i+1) + "\t\t" + score[i]);
            }

        }
    }
}

第二版
using System;

namespace homework5
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("請輸入班級人數");
            int peopleNum = int.Parse(Console.ReadLine());
            double[] score = new double[peopleNum];

            double total = 0;
            double average = 0;

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine("請輸入第" + (i+1) + "位同學的成績");
                score[i] = double.Parse(Console.ReadLine());
                total += score[i];
            }


            Console.WriteLine("編號\t\t成績");  // \t可以水平定位
            Console.WriteLine("--------------------");

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine((i+1) + "\t\t" + score[i]);
            }
            Console.WriteLine("--------------------");

            average = total / peopleNum;

            Console.WriteLine("平均\t\t" + average);


        }
    }
}

第三版
using System;

namespace homework5
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("請輸入班級人數");
            int peopleNum = int.Parse(Console.ReadLine());
            double[] score = new double[peopleNum];

            double total = 0;
            double average = 0;
            int fail = 0;

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine("請輸入第" + (i+1) + "位同學的成績");
                score[i] = double.Parse(Console.ReadLine());
                total += score[i];
                if (score[i] < 60)
                    fail++;
            }


            Console.WriteLine("編號\t\t成績");  // \t可以水平定位
            Console.WriteLine("--------------------");

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine((i+1) + "\t\t" + score[i]);
            }
            Console.WriteLine("--------------------");

            average = total / peopleNum;

            Console.WriteLine("平均\t\t" + average);
            Console.WriteLine("被當人數\t" + fail);


        }
    }
}

第四版

using System;

namespace homework5
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("請輸入班級人數");
            int peopleNum = int.Parse(Console.ReadLine());
            double[] score = new double[peopleNum];

            double total = 0;
            double average = 0;
            double highest = 0;
            double lowest = 100;
            int fail = 0;

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine("請輸入第" + (i+1) + "位同學的成績");
                score[i] = double.Parse(Console.ReadLine());
                total += score[i];
                if (score[i] > highest) 
                    highest=score[i];
                if (score[i] < lowest)  
                    lowest = score[i];
                if (score[i] < 60)
                    fail++;
            }


            Console.WriteLine("編號\t\t成績");  // \t可以水平定位
            Console.WriteLine("--------------------");

            for (int i = 0; i < peopleNum; i++)
            {
                Console.WriteLine((i+1) + "\t\t" + score[i]);
            }
            Console.WriteLine("--------------------");

            average = total / peopleNum;

            Console.WriteLine("平均\t\t" + average);
            Console.WriteLine("最高分\t\t" + highest);
            Console.WriteLine("最低分\t\t" + lowest);
            Console.WriteLine("被當人數\t" + fail);


        }
    }
}