Write a program that reads a set of floating-point data values that uses an appr

Question

Write   a   program   that   reads   a   set   of   floating-point   data   values   that   uses   an   appropriate   sentinel   for   indicating   the  
end   of   the   data   set.   When   all   values   have   been   read,   print   out   the   count   of   the   values,   the   average,   and   the  
standard   deviation.       Notes:   The   average   of   a   data   set   {   x1, . . ., xn }   is:

where   n   is   the   number   of   input   values.   The   standard   deviation   is:      

You   can   compute   this   quantity   by   keeping   track   of   the   count,   the   sum,   and   the   sum   of   squares   as   you   process  
the   input   values.
  Enter numbers - Q to quit: 1 2 3 4 5 6 q
n = 6, average = 3.5, standard deviation = 1.87083

Enter numbers - Q to quit: 1.1 3.3 4.4 6.6 9.9 q

Explanation / Answer

#include <iostream>
#include <cmath>
#include <cstdio>
#include <cstdlib>

using namespace std;

int main()
{
float sum=0.0,sum_sq=0.0,x;
int n=0;
cout<<" Enter the numbers. Enter '-0' to quit ";
while(1)
{
cin>>x;
if(x==-0)
break;
n++;
sum+=x;
sum_sq+=x*x;
}
cout<<" n = "<<n<<endl;
cout<<" Mean = "<<(sum*1.0/n)<<endl;
cout<<" Standard deviation = "<<pow(((sum_sq-(sum*sum*1.0)/n)*1.0/(n-1)),0.5)<<endl;

}

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