Question

P3.4 Population. In a population, the birth rate is the percentage increase of the population due to births, and the death rate is the percentage decrease of the population due to deaths. Write a program that displays the size of a population for any number of years. The program should ask for the following data: The starting size of a population The annual birth rate The annual death rate The number of years to display Write a function that calculates the size of the population for a year. The formula is NEP+BP-DP where N is the new population size, Pis the previous population size, B is the birth rate, and is the death rate. Input Validation: Do not accept numbers less than 2 for the starting size. Do not accept negative numbers for birth rate or death rate. Do not accept numbers less than 1 for the number of years. C:\Windows\system32\cmd.exe This program calculates population change. Enter the starting population size: 180 Enter the al Mirth rate of sprent Pelation): Enter the tal death rate asx of current platin): 1.5 For how many years de you wish te vle population changes? 20 barting population 1000 Population the end of year 1 is 1815. end of year is 177. of years 1893. he end of year is 11e. the end of year is 1126 end of War is 114). od of War 18 is 116 Population Population Pupatillaria Tamilarlan| Tamilat lan of year 13 I 121). end of year 11 ts 1231. the end of a 15 is 125 the end of year 16 is 1368 the end of War 17 is 1988 the end of WR 18.11. the end of a 19 L. 1326. the end of year 28 - 134. to cente P3.5 isPrime Function. A prime number is a number that is only evenly divisible by itself and 1. For example, the number 5 is prime because it can only be evenly divided by 1 and 5. The number 6, however, is not prime because it can be divided evenly by 1, 2,3, and 6. Write a function name ia prime, which takes an integer as an argument and returns true if the argument is a prime number, or false otherwise. Write a main function that makes use of the iskrime function to display all prime numbers from 1 through 100. Note: display five prime numbers per line as shown in the sample display. Windows\system32\endeve "16 عدواء هدا معاهده پDila se balea are inl | 3 19 11 21 SY IRI 127 197 Press any otecen...

Answer 1

Below is the program in C++ for the requirements mentioned in the question. It contains a function population_change() which calculates the population for every next year based on the valid birth rate and death rate. Population is rounded off as shown in the question to the closest intger using the round() function in C++. All the invalid input cases are handled. Sample output is attached at the end showing the behavior of program on all valid inputs and on one of the invalid input given by the user.

#include <iostream>
#include <cmath>
using namespace std;

// function calculating population change every year.
// round off the population to nearest integer.
void population_change(double currpop, double birth, double death, int years){
    
    for(int i = 1; i <= years; i++){
        currpop = currpop + (birth*currpop)/100 - (death*currpop)/100;
        currpop = round(currpop);
        cout<<"Population at the end of year "<<i<<" is "<<currpop<<endl;
    }
    
}

int main()
{
    cout<<"This program calculates population change.\n";
    double pop;
    double brate, drate;
    int nyears;
    cout<<"enter the starting size of the population: ";
    cin>>pop;
    // handling invalid population case.
    if(pop < 2){
        cout<<"Population size less than 2 which is invalid.";
        return 0;
    }
    
    cout<<"enter the annual birth rate (as % of current population): ";
    cin>>brate;
    // handling invalid birth rate case.
    if(brate < 0){
        cout<<"birth rate is negative which is invalid.";
        return 0;
    }
    
    
    cout<<"enter the annual death rate (as % of current population): ";
    cin>>drate;
    // handling invalid death rate case.
    if(drate < 0){
        cout<<"death rate is negative which is invalid.";
        return 0;
    }
    
    cout<<"For how many years do you wish to view population change? ";
    cin>>nyears;
    // handling invalid number of years case.
    if(nyears < 1){
        cout<<"number of years are less than 1 which is invalid.";
        return 0;
    }
    
    
    cout<<endl;
    cout<<"starting population: "<<pop<<endl<<endl;

    // calling the function to calculate population change.
    population_change(pop, brate, drate, nyears);
    
    return 0;
}

Sample Output:-

Output when all the values are valid.

This program calculates population change. enter the starting size of the population: 1000 enter the annual birth rate (as & of current population) : 3 enter the annual death rate (as & of current population) : 1.5 For how many years do you wish to view population change? 20 starting population: 1000 Population at the end of year 1 is 1015 Population at the end of year 2 is 1030 Population at the end of year 3 is 1045 Population at the end of year 4 is 1061 Population at the end of year 5 is 1077 Population at the end of year 6 is 1093 Population at the end of year 7 is 1109 Population at the end of year 8 is 1126 Population at the end of year 9 is 1143 Population at the end of year 10 is 1160 Population at the end of year 11 is 1177 Population at the end of year 12 is 1195 Population at the end of year 13 is 1213 Population at the end of year 14 is 1231 Population at the end of year 15 is 1249 Population at the end of year 16 is 1268 Population at the end of year 17 is 1287 Population at the end of year 18 is 1306 Population at the end of year 19 is 1326 Population at the end of year 20 is 1346

Output when population is invalid.

This program calculates population change. enter the starting size of the population: 1 Population size less than 2 which is invalid. ... Program finished with exit code 0

Output when birth rate is negative.

This program calculates population change. enter the starting size of the population: 1000 enter the annual birth rate (as % of current population) birth rate is negative which is invalid.

Output when death rate is negative.

This program calculates population change. enter the starting size of the population: 1000 enter the annual birth rate (as % of current population) : 0 enter the annual death rate (as % of current population): -1.5 death rate is negative which is invalid. ... Program finished with exit code 0

Output when years are less than 1.

This program calculates population change. enter the starting size of the population: 1000 enter the annual birth rate (as ; of current population) : 3 enter the annual death rate (as % of current population): 1.5 For how many years do you wish to view population change? 0 number of years are less than 1 which is invalid. ..Program finished with exit code 0