C :

#include<stdio.h>
#include<string.h>
#include<ctype.h>

int main()
{
	int i,n;
	char c,a[201];
	while(scanf("%c%*c%s%*c",&c,a)!=EOF)
	{
		for(n=i=0;i<strlen(a);i++)
			if(c==tolower(a[i])||c==toupper(a[i]))
				n++;
		printf("%.5f\n",n*1.0/strlen(a));
	}
	return 0;
}

C++ :

#include<stdio.h>
#include<string.h>
#include<ctype.h>

int main()
{
	int i,n;
	char c,a[201];
	while(scanf("%c%*c%s%*c",&c,a)!=EOF)
	{
		for(n=i=0;i<strlen(a);i++)
			if(c==tolower(a[i])||c==toupper(a[i]))
				n++;
		printf("%.5f\n",n*1.0/strlen(a));
	}
	return 0;
}

Pascal :

var a,b:string;
    i:integer;
    s:real;
begin
  while not eof do begin
    readln(a);b:=copy(a,1,1);s:=0;
    delete(a,1,2);a:=upcase(a);b:=upcase(b);
    for i:=1 to length(a) do 
      if a[i]=b then s:=s+1;
    writeln(s/length(a):0:5);
  end;
end.
    

Java :

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNext()){
			char c = in.next().charAt(0);
			if(c<='Z')c = (char) (c-'A'+'a');
			String s = in.next();
			int cou = 0;
			for(int i=0;i<s.length();i++){
				char tem = s.charAt(i);
				if(tem<='Z')tem = (char) (tem-'A'+'a');
				if(tem==c)cou++;
			}
				
			System.out.printf("%.5f\n", (float)cou/(float)s.length());
		}
	}

}

Python :

import sys
for line in sys.stdin:
    data = line.split()
    a = data[0].lower()
    b = data[1].lower()
    c = b.count(a)
    d = len(data[1])
    print '%0.5f'%(float(c)/d)

C# :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string str;
            while ((str=Console.ReadLine())!=null)
            {
                str = str.ToLower();
                string[] ans = str.Split(' ');
                char ch=ans[0][0];
                int num = ans[1].Split(ch).Length-1;
                double result = num * 1.0 / ans[1].Length;
                Console.WriteLine(result.ToString("f5"));
            }
        }
    }
}