In an examination, 36% of students failed in Science and 42% failed in Math while 20% failed in both the subjects. If the number of students who passed in only Math is 2800, then determine the total number of students who failed for either one or both subjects in the examination.

To solve this problem, we need to understand that the total percentage of students who failed in either Science, Math, or both is the sum of the students who failed in Science and Math, minus the students who failed in both (to avoid double-counting).

1. First, add the percentage of students who failed in Science and Math: 36% + 42% = 78%.

2. Then, subtract the percentage of students who failed in both subjects: 78% - 20% = 58%. This is the percentage of students who failed in either one or both subjects.

3. We know that the number of students who passed in only Math is 2800, which corresponds to the remaining percentage of students, i.e., 100% - 58% = 42%.

4. Therefore, if 42% corresponds to 2800 students, we can find the total number of students by setting up the following proportion: 42/100 = 2800/Total. Solving for Total gives us Total = 2800 * 100 / 42 ≈ 6667 students.

5. Finally, to find the number of students who failed in either one or both subjects, we multiply this total by the percentage we found in step 2: 6667 * 58/100 ≈ 3867 students.

So, approximately 3867 students failed in either one or both subjects in the examination.