Question

Which expression can be used to check if an integer x is a multiple of 5 within the range 20 to 50 inclusively?

Select one:

a. (x >= 20 && x % 5 == 0) || (x <= 50 && x % 5 == 0)

b. x <= 50 && x >= 20 && x % 5 == 0

c. 20 <= (x % 5) <= 50

d. (x % 5 == 0) && (20 <= x <= 50)

Answer 1

Answer B is correct

x <= 50 && x >= 20 && x % 5 == 0

Explanation:

#include <iostream>
using namespace std;

int main()
{
    int x;
    cout<<"enter a number"<<endl;
    cin>>x;
    if(x <= 50 && x >= 20 && x % 5 == 0){
        // this expression is true for all multiple of 5
        cout<<"expression give true result"<<endl;
    }
    else{
        cout<<"expression give false result"<<endl;
    }

    return 0;
}

Option B :Answer option

Output:1 (for 15 it gives false result because it is less than 20)

Output 2:(for 25 it give true because it is a multiple of 5 and in a range of 20 and 50)

Option A:(x >= 20 && x % 5 == 0) || (x <= 50 && x % 5 == 0)(Wrong)

Proof:This expression give true for all values which give x%5==0

Opction C: 20 <= (x % 5) <= 50 (wrong)

Proof: This expression give true for all values of x

Option D: (x % 5 == 0) && (20 <= x <= 50) (Wrong)

Proof: This expression give true for all values which give x%5==0