Question

Let A = (x:x is a natural number less than 10 and
a multiple of 3), and B = {1,2,3,4,5)

(b) Write (i) AUB (ii) A-B
​

Answer 1

Answer:

41

Step-by-step explanation:

S={x:x is a positive multiple of 3 less than 100}

⟹S={3,6,9,12,⋯,99}

⟹n(S)=33

P={x:x is a prime number less than 20}  

⟹P={2,3,5,7,11,13,17,19}

⟹n(P)=8

n(S)+n(P)=33+8=41

Answer 2

Answer:

A = {3,6,9}

B = {1,2,3,4,5}

i) AUB = {1,2,3,4,5,6,9}

ii) A - B = {6,9}