C++ :

#include <iostream>
#include <iomanip>
using namespace std;

int main(){
	int a[20];
	int m,n,i;
	double s = 0.0;
	cin>>m>>n;
	
	for(i = 0;i < n;i++){
		cin>>a[i];
		s = s + a[i];
	}
	
	s = s / n;
	s = s * m;
	
	cout<<fixed<<setprecision(1)<<s<<endl;
}

Pascal :

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

Java :

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int m = sc.nextInt();
		int n = sc.nextInt();
		int[] a = new int[n];
		for (int i = 0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		double s = 0;
		for (int i = 0;i<n;i++) {
			s=s+a[i];
		}
		double ave = s / n ;
		double t = ave * m ;
		System.out.println(String.format("%.1f", t));
	}
}

Python :

a = input().split()
b = input().split()
# 橘子的总个数m
m = int(a[0])
# 小明称的橘子的个数
n = int(a[1])
l = []
su = 0
av = 0
s = 0
#b字符串列表转换成整型列表l
for v in b:
    l.append(int(v))
#遍历l列表,求出总和
for v in l:
    su += v
#求出平均一个橘子的重量
av = su / len(l)
#求出总重量
s = av * m
#打印输出
print('%.1f' % s)