Question 184847:  Please help me with the following question. Ireally need the help my work is due today and I just don't get it. 
1.Set K contains 30 elements, set J contains 46 elements, and 11 elements are common to both sets. Find n ( K U J). 
 
2.Given A = {1, 2, 3},  B = {3, 4, 5, 6,}, and C = {3, 5, 7}. Evaluate each set  
a)	A ∩ B 
b)	A ∩ C 
c)	A U C 
d)	B U C 
e)	(A U B) ∩ C 
f)	A U (B U C) 
g)	(A ∩ B) ∩ C 
h)	(A ∩ B) U C
 
Please help me 
 Answer by jim_thompson5910(35256)      (Show Source): 
You can  put this solution on YOUR website! # 1
 
 
To find the number of elements in the set K U J, simply add the two sets together. However, remember to subtract the number of elements in both sets (since these elements are repeated)
 
 
 
In other words, use this formula:
 
 
n ( K U J) = n(K) + n(J) - n(K ∩ J)
 
 
 
In this case, n(K)=30, n(J)=46 and n(K ∩ J) = 11. Plug these values in to get:
 
 
n ( K U J) = 30 + 46 - 11
 
 
 
Add
 
 
n ( K U J) = 76 - 11
 
 
 
Subtract
 
n ( K U J) = 65
 
 
 
So there are 65 elements in set K U J
 
 
 
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# 2
 
 
I'll do the first four to get you started
 
 
a)
 
 
A ∩ B = Set of elements that BOTH sets A and B have in common 
 
 
A ∩ B = {1, 2, 3} ∩ {3, 4, 5, 6}
 
 
A ∩ B = {3}
 
 
----------------
 
 
b) 
 
 
A ∩ C = Set of elements that BOTH sets A and C have in common 
 
 
A ∩ C = {1, 2, 3} ∩ {3, 5, 7}
 
 
A ∩ C = {3}
 
 
----------------
 
c)
 
 
A U C = Combination of the sets A and C (remove any duplicates)
 
 
A U C = {1, 2, 3} U {3, 5, 7}
 
 
A U C = {1,2,3,5,7}
 
 
----------------
 
d)
 
 
B U C = Combination of the sets B and C (remove any duplicates)
 
 
B U C = {3, 4, 5, 6} U {3, 5, 7}
 
 
B U C = {3,4,5,6,7} 
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