JEE Main202311 Apr 2023Morning ShiftMathematicsSets and RelationsActual
An organization awarded 48 medals in event A ' ' , 25 in event B ' ' and 18 in event C ' ' . If these medals went to total 60 men and only five men got medals in all the three events, then, how many received medals in exactly two of three events?
Options
- A15
- B21
- C10
- D9
Correct answer
B. 21
Step-by-step solution
Let A ,   B and C denote the set of men who received medals in even A , event B and event C respectively. Then, n A = 48 ,   n B = 25 ,   n C = 18 , n A ∪ B ∪ C = 60 and n A ∩ B ∩ C = 5 , Now we know that, n A ∪ B ∪ C = n A + n B + n C - n A ∩ B - n A ∩ C - n B ∩ C + n A ∩ B ∩ C ⇒ 60 = 48 + 25 + 18 - n ( A ∩ B ) - n ( A ∩ C ) - n ( B ∩ C ) + 5 ⇒ n ( A ∩ B ) + n ( A ∩ C ) + n ( A ∩ C ) = 4