Question

/*
The following function receives the class marks for all student in a course and compute standard deviation. Standard deviation is the average of the sum of square of difference of a mark and the average of the marks. For example for marks={25, 16, 22}, then average=(25+16+22)/3=21. Then standard deviation = ((25-21)^2 + (16-21)^2+(22-21)^2)/3.
Implement the function bellow as described above. Then write a test console app to use the function for computing the standard deviation of a list of marks that user inputs as floats in the range of 0.f to 100.f. User signals end of the list by entering -1 as final mark. Make sure to verify user input marks are valid and in the range, before processing them.

*/

float ComputeMarksStandardDeviation(std::array<float> marks)
{
}

Answer 1

PROGRAM:

#include<iostream>

#include<vector>

#include<math.h>

using namespace std;

/**The following function receives the class marks

* for all student in a course and compute standard deviation.

* function for computing the standard deviation of a list of

* marks that user inputs as floats in the range of 0.f to 100.f.*/

float ComputeMarksStandardDeviation(std::vector<float> marks){

float sum = 0;

float MarksStandardDeviation;

// find the size of the vector

int n = marks.size();

// calculate the sum of all marks

for(int i=0; i<n; i++){

sum+=marks[i];

}

/**For example for marks={25, 16, 22}, then average=(25+16+22)/3=21. Then

* standard deviation = ((25-21)^2 + (16-21)^2+(22-21)^2)/3.

* calculate the average of marks*/

float average = sum/n;

// calculate the standard deviation

for(int i=0; i<n; i++){

MarksStandardDeviation += pow(marks[i] - average, 2);

}

// return the standard deviation

return MarksStandardDeviation/n;

}

// main() function

int main()

{

float num;

vector<float> marks;

while(true){

cout<<"Enter marks: ";

cin>>num;

// User signals end of the list by entering -1 as final mark.

if(num==-1) break;

// Make sure to verify user input marks are valid and in the range,

// between 0-100f

while(num<0 || num>100){

cout<<"Out of range"<<endl;

cout<<"Enter marks between 0-100: ";

cin>>num;

}

// push_back into the vector marks

marks.push_back(num);

}

// calling and print the standard Deviation

// Standard deviation is the average of the sum

// of square of difference of a mark and the average of the marks

cout<<"Standard Deviation: "<<ComputeMarksStandardDeviation(marks);

return 0;

}

OUTPUT :
Enter marks : 25
Enter marks : 16
Enter marks : 22
Enter marks : -1
Standard deviation : 14