# If S and T are two sets such that S has 21 elements, T has 32 elements, and S ∩ T has 11 elements, how many elements does S ∪ T have?

**Solution:**

It is given that S and T are two sets such that:

n (S) = 21, n (T) = 32 and n (S ∩ T) = 11

We know that n(S υ T) is,

**n (S υ T) = n (S) + n (T) - n (S ∩ T)**

= 21 + 32 - 11

= 53 - 11

= 42

**Therefore, S υ T has 42 elements**

NCERT Solutions Class 11 Maths Chapter 1 Exercise 1.6 Question 4

## If S and T are two sets such that S has 21 elements, T has 32 elements, and S ∩ T has 11 elements; how many elements does S υ T have?

**Summary:**

It is given that S and T are two sets such that S has 21 elements, T has 32 elements, and S ∩ T has 11 elements. We have found that S υ T has 42 elements.