SOLUTION: Hi, can you help with this one: Set X has x members and set Y has y members. Set Z consists of all members that are in either set X or set Y with the exception of the K common

Question 83888: Hi, can you help with this one:
Set X has x members and set Y has y members. Set Z consists of all members that are in either set X or set Y with the exception of the K common members (K > 0). Which of the following represents the number of members in set Z? The answer is x + y - 2K, but I don't understand why I should count K twice since it is the same members in both sets X and Y, I feel like it's duplicating the members, counting them out of set Z twice instead of just once. Thank you for your help.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Draw the picture of two overlapping circles; the overlap has K members
If you exclude the members of X that are in K you have x-K
If you exclude the members of Y that are in K you have y-K
Z has (x-K) + (y-K) members
Z has x+y-2K members
==============
Cheers,
Stan H.
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