Question

Hi everyone,

I have a question which is really hard for me to figure it out i have to code this for c++.

-When deciding about whether or not to install solar panels on your house, it becomes useful

to project ahead as to how much you can expect pacific Gas & electric to raise its electric rates each year.

- The lifetime of a solar installation is about 30 years, so you will want to know how much you'll be saving over the next 30 years.

- If we google the PG&E electric rates (A6 schedule) for 2001, we will find that the average cost of a KiloWatt Hour (KWHr), then was 9.92 cents per KWHr.

- If we check for the rate in 2015, we find it is 20.34 cents per KWHr.

-What we want to find out is, over the intervening 14 years, what is the average rate of increase of the cost of a KWHr, per year?

- To project the new years cost per kilowatt (cpk) from the old years rate, we can simply use the formula.

"newYearCPK=(1+averageRateOfIncrease)*oldYearCPK;"

-If we use a loop to do this for 14 years, then we can test out guesses as to what the averageRateOfIncrease (roi) should be. we may be a bit off on the first guess, so we can make a correction and then try again.

-using another loop, gibe yourself the option of continuing on with another try, or quitting, once your satisfied that you are close enough.

- Repeat this procedure until you can determine to 4 digits (that would be 5.2xy% where you need to determine, by trial and error what the values of x and y are) the average rate of increase per year.

Answer 1

C++ code for the problem is provided below, please comment if any doubts:

C++ code:

#include<iostream>

using namespace std;

//The main function
int main()
{
   //set the local variables
   float averageRateOfIncrease=0.052;
   float firstYCPK=9.92;
   float lastYCPK=20.34;

   //the for loop to trial and error since
   //the value is obaines
   for(;;)
   {
       float oldYearCPK=firstYCPK;
       float newYearCPK=0;
       //iterate 14 years
       for(int i=0; i<14; i++)
       {
           newYearCPK=(1+averageRateOfIncrease)*oldYearCPK;
           oldYearCPK=newYearCPK;

       }

       //If the approximate value reached
       if(abs(newYearCPK-lastYCPK)<=0.001)
           break;

       //else try next trial
       else averageRateOfIncrease=averageRateOfIncrease+0.00001;

   }
   //compute the percentage value
   float inPercent = averageRateOfIncrease*100;
   //Print the result
   printf("The average rate of increase = %.3f ", inPercent);
   return 0;
}

Output screenshot: