Sets Relations And Functions Question 106
Question: If n = 115, n = 326, n(A - B) = 47, then what in $ n(A\cup B) $ equal to?
Options:
A) 373
B) 165
C) 370
D) 394
Show Answer
Answer:
Correct Answer: A
Solution:
- [a]We know, for two sets A and B $ A-B=A-(A\cap B) $
$ \therefore n(A-B)=n(A)-n(A\cap B) $ Given, $ n(A)=115,n(B)=326 $ and $ n(A-B)=47. $
$ \Rightarrow 47=115-n(A\cap B) $
$ \Rightarrow n(A\cap B)=68 $
Consider $ n(A\cup B)=n(A)+n(B)-n(A\cap B) $
$ =115+326-68=373 $
BETA
