1. 20 men handshake with each other without repetition. What is the total number of handshakes made? a) 190 b) 210 c) 150 d) 250

• ANS: A
  
  To start with first person, he does shake hand with remaining 19 men. second person does shake hand with 18 members and so on...
  
  series becomes as 1+2+3+.....+19 = 19*20/2 =190 (n*(n+1))/2
• 12 years agoHelpfull: Yes(7) No(3)
• Ans: A
  
  20C2 = (20!)/2!(20-2)! = 20!/2!*18! = 20*19/2=190
• 12 years agoHelpfull: Yes(3) No(0)
• Here I have two ways:
  
  1..Using formula n(n-1)/2
  =20(20-1)/2
  =20(19)/2
  =190
  
  2.. 20 mens handshake = 19+18+17+....+1=190
  
  
• 12 years agoHelpfull: Yes(2) No(0)