Question

1) Develop a C++ function that determines the average value of an array of type double elements

• double GetAverage(double array[], int size)
• The function should accept as input an array of double values
• The function should accept as input the number of elements in the array of double values
• The function should return a double value which is the array's average value

2) Develop a C++ function that determines the variance of an array of type double elements

• double GetVariance(double array[], int size)
• The function should accept as input an array of double values
• The function should accept as input the number of elements in the array of double values
• The function should return a double value which is the array's variance
• Use the average value function you created above to compute the variance value

• σ² = variance
• ∑ (X - µ)² = The sum of (X - µ)² for all data points
• X = individual data points
• µ = average/mean of the data points
• N = number of data points

3) Develop a C++ program that determines and displays the average value and variance of an array of type double elements

• For your testing, please copy/paste the following data into your program:

const int NUMBER_OF_TEST_SCORES = 19;
double TestScores[NUMBER_OF_TEST_SCORES] = { 180, 122.5, 153, 180, 180, 157.5, 178, 178, 198, 168, 150, 162, 154, 188, 195, 180, 176, 168, 153 };

• With this data, your results should display as follows:
  • The average is 169.5263158
  • The variance is 316.3808864

Answer 1

CODE -

#include<bits/stdc++.h>

using namespace std;

// Function to compute average of the array.

double GetAverage(double array[], int size)

{

    float sum = 0;

    // This loop computes sum of all elements of the array.

    for(int i=0;i<size;i++)

        sum += array[i];

    return (sum/size);          // Returning sum divided by size of array which is equal to average of the array.

}

// Function to compute variance of the array.

double GetVariance(double array[], int size)

{

    double sum_sq_diff = 0;

    double avg = GetAverage(array,size);        // Calling GetAverage function to get the average of the array.

    //This loop computes the Sum Squared Differences with mean.

    for(int i=0;i<size;i++)

        sum_sq_diff += ((array[i] - avg) * (array[i] - avg));

    return (sum_sq_diff/size);                  // Returning sum_sq_diff divided by size of array which is equal to Variance.

}

// Main function to test above functions.

main()

{

    const int NUMBER_OF_TEST_SCORES = 19;

    double TestScores[NUMBER_OF_TEST_SCORES] = { 180, 122.5, 153, 180, 180, 157.5, 178, 178, 198, 168, 150, 162, 154, 188, 195, 180, 176, 168, 153 };

    cout << "The average is " << fixed << setprecision(7) << GetAverage(TestScores,NUMBER_OF_TEST_SCORES) << endl;

    cout << "The variance is " << fixed << setprecision(7) << GetVariance(TestScores, NUMBER_OF_TEST_SCORES) << endl;

    // setprecision was used so that the values don't get trimmed after decimal places.

}

SCREENSHOT -