Question

Average and Standard Deviation of 4 numbers

**c++**

Write an input function to input 4 doubles. then write a function that computes the average of 4 doubles and returns the average and the standard deviation. Write a output routine that shows the 6 numbers. Please feel free to use sub-functions to break up your code.   

you can name the four variables a1, a2, a3, a4, or something equally simple as long as you are consistent.

Average (or mean) is the sum of the four variables divided by 4.

Standard Deviation is shown below.

do not use vectors or arrays

(x - mean) x is a set of numbers mean is the average of the set of numbers n is the size of the set o is the standard deviation

Answer 1

#include<iostream>
#include<cmath>

using namespace std;

void getInput(double & d1,double & d2,double & d3,double & d4){
  
   cout<<"Enter 1st number: ";
   cin>>d1;
   cout<<"Enter 2nd number: ";
   cin>>d2;
   cout<<"Enter 3rd number: ";
   cin>>d3;
   cout<<"Enter 4th number: ";
   cin>>d4;
  
}

void getStats(double d1,double d2, double d3, double d4, double &avg, double &std ){
   double sum = (d1+d2+d3+d4)*1.0;
   avg = sum/4.0;
   double term;
   term = pow((d1-avg),2)+pow((d2-avg),2)+pow((d3-avg),2)+pow((d4-avg),2);
   std = pow(term/4.0,.5);
}

void display(double d1,double d2, double d3, double d4, double avg, double std ){
   cout<<"\nNumber 1: "<<d1;
   cout<<"\nNumber 2: "<<d2;
   cout<<"\nNumber 3: "<<d3;
   cout<<"\nNumber 4: "<<d4;
   cout<<"\nAverage: "<<avg;
   cout<<"\nStandard deviation: "<<std;
}

int main(){
   double d1,d2,d3,d4,avg,std;
   getInput(d1,d2,d3,d4);
   getStats(d1,d2,d3,d4,avg,std);
   display(d1,d2,d3,d4,avg,std);
   return 0;
  
  
}

Enter 1st number: 45.3 Enter 2nd number: 54.3 Enter 3rd number: 56.4 Enter 4th number: 64.3 Number 1: 45.3 Number 2: 54.3 Number 3: 56.4. Number 4: 64.3 Average: 55.075 Standard deviation: 6.76401 ------------------------- Process exited after 8.549 seconds with return value o Press any key to continue ...