Question

3. Suppose set \( A \) consists of first 250 natural numbers that are multiples of 3 and set \( B \) consists of first 200 even natural numbers. How many elements does \( A \cup B \) have? (a) 324 (b) 364 (c) 384 (d) 400

Answer 1

Given: n(A)=250

             n(B)=200

A={3,6,9,12,.......750}

B=2,4,6,8,10.......400}

Therefore,A⋂B={6,12,18....396)

                  =>n(A⋂B)=396/6=66

 

n(A∪B)=n(A)+n(B)-n(A⋂B)

              =250+200-66

              =384

Hence,the correct answer is option (c)384