Question

Let A = {x : x is positive integral multiple of 3 less than 31} and B = { x : x is prime number less than 30}, Then n(AUB) + n(AՈB) is equal to: 
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Answer 1

Answer:

20

Step-by-step explanation:

A=(3,6,9,12,15,18,21,24,27,30)

An= 10

B =(2,3,5,7,11,13,17,19,23,29)

Bn= 10

n(AUB)=An+Bn-n(A inter. B)

n(AUB) = 10+10-1

             =19

also     n(AUB)= An+Bn -n(AՈB)

n(AUB) + n(AՈB) = 19+1=20

Answer 2

Step-by-step explanation:

Given that:

Let A = {x : x is positive integral multiple of 3 less than 31} and B = { x : x is prime number less than 30}, Then n(AUB) + n(AՈB) is equal to: 

To find:n(AUB) + n(AՈB)

Solution:

Write A and B in roaster form,for easy understanding

A = {x : x is positive integral multiple of 3 less than 31}

A:{3,6,9,12,15,18,21,24,27,30}

B = { x : x is prime number less than 30}

B={2,3,5,7,11,13,17,19,23,29}

1) Find: AUB

AUB= {2,3,5,6,7,9,11,12,13,15,17,18,19,21,23,24,27,29,30}

n(AUB)=19

2) Find: AՈB

AՈB={3}

n(AՈB)=1

So,

n(AUB) + n(AՈB)= 19+1= 20

Final Answer: n(AUB) + n(AՈB)= 20

Hope it helps you.

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