Multiple choice general knowledge

Every person in a room shook hans with every OTHER person in the room. Totally there were 105 hand shakes .Find the total persons in the room

  1. 10

  2. 10.5

  3. 21

  4. 14

  5. 15

  6. 12
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

For n persons each shaking hands with every other person, total handshakes = n(n-1)/2. If handshakes = 105, then n(n-1) = 210, giving n = 15. Check: 15 × 14/2 = 105.

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