Find the cardinal number of the indicated set. Use the cardinal number formula.
-If $n ( B ) = 60 , n ( A \cap B ) = 11$, and $n ( A \cup B ) = 105$, find $n ( A )$.
A) 54
B) 56
C) 45
D) 58

Question

Quizplus · Accepted Answer

The formula for finding the number of elements in the union of two sets is $n(A \cup B) = n(A) + n(B) - n(A \cap B)$. Plugging in the given values, we get $105 = n(A) + 60 - 11$. Solving for $n(A)$, we find $n(A) = 56$.

Find the Cardinal Number of the Indicated Set n(B)=60,n(A∩B)=11n ( B ) = 60 , n ( A \cap B ) = 11n(B)=60,n(A∩B)=11

Find the Cardinal Number of the Indicated Set $n ( B ) = 60 , n ( A \cap B ) = 11$