Question

Write a program that computes the average and standard deviation of four scores. The standard deviation is defined to be the square root of the average of the four values. Use two functions. One function to calculate the average, this function should be with Return Type "double". Second Function should be to calculate standard deviation, this function should be with Return Type "void". Allow the program to continue until the user tells the program he/she is finished.

This is for C++

The program must use at least 2 programmer defined functions

The program must match the Return Type constraints

The program must continue calculations as long as user wishes (ie: use a do while loop) "Enter y to run the program again or n for no"

average = (s1 + s2 + s3 + s4) / 4

The standard deviation is computed as

standard_deviation = sqrt( ( (s1 -average)² + (s2 - average)² + ( s3 - average)² + (s4 - average)²  )/4 ).

SAMPLE OUTPUT

Enter four decimal numbers =>12.3 13.4 10.5 9.0
The average = 11.3
The standard deviation of these numbers = 1.68375
Please enter y to continue =>y

Enter four decimal numbers =>1 2 3 4
The average = 2.5
The standard deviation of these numbers = 1.11803
Please enter y to continue =>n

Answer 1

Following is the answer:

#include <iostream>
#include <cmath>
using namespace std;
  
// Function that return average
double average(double array[])
{
double sum = 0;
for (int i=0; i<4; i++) {
sum += array[i];
}
return sum/4;
}

// Function that return deviation.
double deviation(double array[])
{
double standardDeviation = 0.0;

for (int i=0; i<4; i++) {
standardDeviation += pow(array[i]- average(array),2);
}
cout<<"The standard deviation of these numbers = "<<sqrt(standardDeviation/4)<<endl;
}
  
// Driver code
int main()
{
int n = 4;
double array[4];
  
char ch;
do{
cout<<"Enter four decimal numbers => ";
for(int i = 0 ; i < n ; i++){
cin>>array[i];
}
  
cout << "The average = "<<average(array) << endl;
deviation(array);
  
cout<<"Please enter y to continue =>";
cin>>ch;
cout<<endl;
}while(ch != 'n');
return 0;
}

Output:

Enter four decimal numbers => 12.3 13.4 10.5 9.0 The average = 11.3 The standard deviation of these numbers = 1.68375 Please enter y to continue =>y Enter four decimal numbers => 1 2 3 4 The average = 2.5 The standard deviation of these numbers = 1.11803 Please enter y to continue =>n