Question

You have been asked to write a program to grade several multiple-choice exams. The

exam has 20 questions, each answered with a letter in the range of ‘a’ through ‘f’. The

answers key is declared in the program as constant of type string. An example of answer

key is “abcdefabcdefabcdefab”. Your program should work for any other answer key.

The program should first ask users for the number of students to be graded. Then it

should have a while loop in the main function. For each student, the loop repeatedly asks

users to enter a student ID number and a string of characters representing the answers of

the student. The student ID number is of type string and should contain exactly 7 digits

(each digit between ‘0’ and’9’). If a student ID number is incorrect, the program displays

and error message and prompts the user to re-enter that student information. If a student

gives more answers than necessary (more than 20 in our case), the program automatically

truncates the extra answers. On the other hand, if a student provides less number of

answers, the remaining unanswered questions are considered as being answered wrongly.

If for a given answer, the user enters a letter other than ‘a’, b’, ‘c’, ‘d’, ‘e’, or ‘f’ then the

question is considered as being wrongly answered.

Furthermore, in each while loop in the main routine, your program should compute a

percentile score for the student by comparing the answers for that student to the answers

key, and a curved grade in ‘A’ though ‘F’ based on the following:



>=90

A



<90 and >=80

B



<80 and >= 70

C



<70 and >= 60

D



<60 and >= 50

E



<50

F

The results of each student are displayed by the student in the format: percentile score

and a curved grade in ‘A’ though ‘F’.

The program should also compute and display the following statistics for the graded

answers: Average score, Maximum score, and Minimum score.

Use the following inputs to test your program:

Answer key = abcdefabcdefabcdefab

abbcdaefcdffbceffadbc

Please enter the number of students to be graded: 5

For each of the following students, enter the Student ID and answers:

Student 1: 1234567 abcdefabcdefabcdefab

Score: 100% A

Student 2: 9876543 abddefbbbdefcbcdefac

Score: 75% C

Student 3: 555444656 abcdefabcdefabcd

ERROR in the Student ID number. Please re-enter Student 3 information:

Student 3: 5554446 abcdefabcdefabcd

Score: 80% B

Student 4: 4445556 abcdefabcdefabcdefabcdaedf

Score: 100% A

Student 5: 5551112 abbcdaefcdffbceffadbc

Score: 30% F

Statistics:

Average Score: 75%

Minimum Score: 100%

Maximum Score: 30%

The score of student 5 is 30% (6/20). Student 5 gives 21 answers, compared to 20

answers in the key. We discard any extra answers, which are more than 20.

To provide solutions to this project, you need to deliver the following components on the

basis of principles in software engineering.

Answer 1

// C++ program to calculate the grades for students for multiple choice exam

#include <iostream>

#include <cctype>

using namespace std;

// function declaration

bool isStudentIdValid(string studID);

int main() {

               string answer = "abcdefabcdefabcdefab"; // correct answers

               int numStudents;

               int totalScore = 0,minScore = answer.length(),maxScore = 0;

               int score;

               string studId, stud_ans;

               // input for number of students

               cout<<" Please enter the number of students to be graded: ";

               cin>>numStudents;

               cout<<" For each of the following students, enter the Student ID and answers: "<<endl;

               int i=1;

               // loop to input student data and calculate its grade

               while(i <= numStudents)

               {

                              cout<<" Student "<<i<<" : ";

                              cin>>studId>>stud_ans;

                              // validate the student id

                              while(!isStudentIdValid(studId))

                              {

                                             cout<<" ERROR in the Student ID number. Please re-enter Student "<<i<<" information: "<<endl;

                                             cout<<" Student "<<i<<" : ";

                                             cin>>studId>>stud_ans;

                              }

                              score = 0;

                              // calculate the score

                              if(stud_ans.length() < answer.length())

                              {

                                             for(int j=0;j<stud_ans.length();j++)

                                             {

                                                            if(tolower(stud_ans.at(j)) == tolower(answer.at(j)))

                                                                           score++;

                                             }

                              }else{

                                             for(int j=0;j<answer.length();j++)

                                             {

                                                            if(tolower(stud_ans.at(j)) == tolower(answer.at(j)))

                                                                           score++;

                                             }

                              }

                              // update maxScore and minScore

                              if(maxScore < score)

                                             maxScore = score;

                              if(minScore > score)

                                             minScore = score;

                              int score_percent = ((score*100)/answer.length());

                              totalScore += score;// add to totalScore

                              cout<<" Score : "<<score_percent<<"% ";

                              if(score_percent >= 90)

                                             cout<<"A"<<endl;

                              else if(score_percent >=80)

                                             cout<<"B"<<endl;

                              else if(score_percent >=70)

                                             cout<<"C"<<endl;

                              else if(score_percent >=60)

                                             cout<<"D"<<endl;

                              else if(score_percent >=50)

                                             cout<<"E"<<endl;

                              else

                                             cout<<"F"<<endl;

                              i++;

               }

               cout<<" Statistics : "<<endl;

               cout<<" Average Score: "<<(totalScore*100)/(answer.length()*numStudents)<<"%"<<endl;

               cout<<" Minimum Score: "<<(minScore*100)/(answer.length())<<"%"<<endl;

               cout<<" Maximum Score: "<<(maxScore*100)/(answer.length())<<"%"<<endl;

               return 0;

}

// function to determine if the student id is valid or not

bool isStudentIdValid(string studID)

{

               if(studID.length() != 7)

                              return false;

               for(int i=0;i<studID.length();i++)

                              if(studID.at(i) < '0' || studID.at(i) > '9')

                                             return false;

               return true;

}

//end of program

Output: