Question

Vector testGrades contains NUM_VALS test scores. Write a for loop that sets sumExtra to the total extra credit received. Full credit is 100, so anything over 100 is extra credit. Ex: If testGrades = {101, 83, 107, 90}, then sumExtra = 8, because 1 + 0 + 7 + 0 is 8.

Answer 1

Answer:

Here is for loop that sets sumExtra to the total extra credit received. I am writing a program in C++

for(i = 0; i <= testGrades.size() - 1; i++){

  if(testGrades.at(i) > 100){

      sumExtra = sumExtra + (testGrades.at(i) - 100);   } }

Explanation:

The complete program is:

#include <iostream> //to use input output functions

#include <vector> //to use vectors

using namespace std; //to identify objects like cin cout

int main() { //start of main function

const int NUM_VALS = 4; // sets the value of NUM_VALS as a constant to 4

vector<int> testGrades(NUM_VALS); // initialize the vector of int (integer) type

int i = 0; // i is initialzed to 0

int sumExtra = 0; //stores the total extra credit

testGrades.at(0) = 101; //sets 101 at first position in vector

testGrades.at(1) = 83; //sets value 83 at second position

testGrades.at(2) = 107; //sets value 107 at third position

testGrades.at(3) = 90; //sets value 90 at fourth position

for(i = 0; i <= testGrades.size() -1; i++){ //loop iterate through each value of in a vector testGrades

  if(testGrades.at(i) > 100){ // if the value in a vector exceeds 100

      sumExtra = sumExtra + (testGrades.at(i) - 100);   } } //computes total extra credit

cout << "sumExtra: " << sumExtra << endl;} //displays the value of computed total extra credit in output

The loop works as follows:

In the first iteration the value of vector testGrades at(i) is at(0) = 101.

if statement checks if this value/element is greater than 100. This is true as 101 > 100. So sumExtra = sumExtra + (testGrades.at(i) - 100); statement is executed in which 100 is subtracted from that element and the result is added to the sumExtra. sumExtra is initialized to 0 so the value of sumExtra becomes: 0+ 101 - 100= 1 So the value of sumExtra = 1

In the second iteration the value of i = 1 and it is positioned at 2nd value of vector testGrades i.e. 83. Then if statement checks if this value/element is greater than 100. This is false as 83 < 100. So the value of sumExtra = 1

In the third iteration the value of i = 2 and it is positioned at 3rd value of vector testGrades i.e. 107. Then if statement checks if this value/element is greater than 100. This is true as 107 > 100.

sumExtra = sumExtra + (testGrades.at(i) - 100); statement is executed in which 100 is subtracted from that element and the result is added to the sumExtra

sumExtra is 1 so the value of sumExtra becomes: 1+ 107 - 100= 8 So the value of sumExtra = 8

In fourth iteration  the value of i = 3 and it is positioned at 4th value of testGrades vector i.e. 90. Then the if statement checks if this element is greater than 100. This is false as 90 < 100. So the value of sumExtra remains 8.  

Finally the loop breaks as the value of i becomes 4. So the output is 8.