Question

Write a program in C++ to calculate the average (mean) and the standard deviation of a list of numbers using vectors.

Your program should...

• Prompt for the number of values the user wishes to enter
• Prompt the user to enter the values one at a time for the number of requested values into a vector
• Calculate and display the Mean and Standard Deviation

The flow of your code should be similar to:

int main()
{
    /**
     Prompt the user and get the number of values to enter
     **/
    
    /**
     Get the values from the user and store in a vector
     **/
    
    /**
     Calculate and display the mean and standard deviation
     **/
    
    return 0;
}

Answer 1

#include <iostream>
#include <vector>
#include <cmath>

using namespace std;

int main()
{
   int n;
    /**
     Prompt the user and get the number of values to enter
     **/
     cout<<"Number of values you wishes to enter: ";
     cin>>n;
    
    /**
     Get the values from the user and store in a vector
     **/
     vector<double> v;
     double val;
     for(int i = 0;i<n;i++){
       cin>>val;
       v.push_back(val);
    }
    
    /**
     Calculate and display the mean and standard deviation
     **/
    double sum = 0;
   for(int i = 0; i<n; i++) {
      sum += v[i];
   }
   double mean = sum/n;
   
    cout<<"Mean = "<<mean<<endl;
    
    double sd = 0;
    for (int i = 0; i<n; i++) {
      sd += pow(v[i] - mean, 2);
   }
   sd = sqrt(sd / (n - 1));
   
   cout<<"Standard deviation = "<<sd<<endl;
    
    return 0;
}