Question:medium

In a group of 50 family members, three medicines are given to fight a virus.
• 40 members received medicine A 
• 30 received medicine B 
• 20 received medicine C 
• 10 received all three medicines How many members received at least two medicines?

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Be very careful with the wording in set theory problems.
"Exactly two" means ( (A cap B setminus C) cup (B cap C setminus A) cup (C cap A setminus B) ). Its size is (x+y+z).
"At least two" means ( (A cap B) cup (B cap C) cup (C cap A) ). Its size is (x+y+z+k).
A common mistake is to stop after finding (x+y+z).
Updated On: May 1, 2026
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