I wrote a small C++ program to calculate the mean and standard deviation of a given data set. Here it is:

#include <iostream>
#include <cmath>
using namespace std;
int main (int argc, char* argv[])
{
int number_of_items;
cout << "How many pieces of data are in the list? ";
cin >> number_of_items;
float list[number_of_items];
// get all the data items
cout << "Please enter the data:" << endl;
int i;
for (i = 1; i <= number_of_items; i++)
{
cout << i << ". "; cin >> list[i];
}
// find the mean (average) of the data
float xbar = 0;
for (i = 0; i <= number_of_items; i++)
xbar = xbar + list[i];
xbar = xbar / number_of_items;
cout << "The mean (average) is " << xbar << "." << endl;
// find the standard deviation
float numerator = 0;
float denominator = number_of_items;
for (i = 1; i <= number_of_items; i++)
numerator = numerator + pow((list[i] - xbar), 2);
float standard_deviation = sqrt (numerator/denominator);
cout << "The standard deviation for the given data is "
<< standard_deviation << "." << endl;
return 0;
}

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