A commitee of 5 is to be chosen from a group of 9 people. No. of ways in which it can be be formed. If 2 particular persons either serve together or no at all and 2 other particular persons refuse to serve with each other is?

Dear jee king

case 1

2 perticular person serve

selecting one person out of other 2 perticular person = ²C1=2

and rest 2 can be selected in =5C2 =10

 

case 2

2 perticular person do not serve

selecting one person out of other 2 perticular person = ²C1=2

and rest 4 can be selected in =5C4 =5

so total ways = 2*10 +2*5 =30

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