Question

In an examination, 31 candidates passed chemistry, 29 passed physics and 3 failed both subjects. If 50 candidates sat for the examination, how many of them passed chemistry only?​

Answer 1

28

Explanation:

To find out how many candidates passed chemistry only, you can use the principle of set theory and the given information.

Let:

A = Set of candidates who passed chemistry.

B = Set of candidates who passed physics.

According to the principle of set theory:

Total candidates who passed at least one subject = Candidates who passed chemistry (A) + Candidates who passed physics (B) - Candidates who passed both subjects

Given information:

Candidates who passed chemistry (A) = 31

Candidates who passed physics (B) = 29

Candidates who failed both subjects = 3

Total candidates (n) = 50

Now, plug in the values:

Total candidates who passed at least one subject = 31 + 29 - 3

Total candidates who passed at least one subject = 57

Now, to find out how many candidates passed chemistry only, subtract the number of candidates who passed both subjects from the total who passed chemistry:

Candidates who passed chemistry only = Candidates who passed chemistry (A) - Candidates who passed both subjects

Candidates who passed chemistry only = 31 - 3

Candidates who passed chemistry only = 28

So, 28 candidates passed chemistry only.