C++ :

#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,i,a[100],x,s=0;
	double s1=0;
	cin>>n;
	for (i=0;i<n;i++) {
		cin>>a[i];
	}
	cin>>x;
	for (i=0;i<n;i++) {
		if (a[i]==x) {
			s++;
		}
	}
	s1=s*1.0/n;
	cout<<fixed<<setprecision(2)<<s1<<endl;

	return 0;
}

Pascal :

var a:array[1..100000] of longint;
i,n,b,s:longint;
c:real;
begin
read(n);
for i:=1 to n do
read(a[i]);
read(b);
for i:=1 to n do
if a[i]=b then inc(s);
c:=s/n;
write(c:0:2);
end.

Java :

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] a =new int[n];
		for (int i =0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		int x = sc.nextInt();
		int c = 0 ;
		for (int i =0;i<n;i++) {
			if (a[i]==x) {
				c++;
			}
		}
		double y =(double)c/n;
		System.out.println(String.format("%.2f", y));
	}
}

Python :

# 输入袋子里球的个数n
n = int(input())
# 输入n个球各是什么数字
m = input().split()
# 要判断概率的数字x
x = int(input())
# 定义空列表
l = []
# 记录要判断的数在列表中有多少个
c = 0
# 字符列表转换成整型列表
for v in m:
    l.append(int(v))
# 遍历l列表,找出等于x的个数
for i in range(0, n):
    if l[i] == x:
        c += 1
# 输出概率
print('%.2f' % (c / len(l)))