Question

let A=(x:x is postive integer multiple of 3 less than 31 and B=x:x is prime number less than 3a then (AUB) + (AUB) option 20 ,21, 10 ,none of these
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Answer 1

Answer:

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