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In a birthday party,7 friends meet.each friends shook hands with each other exactly once.how many shake hands are there?
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In a birthday party,7 friends meet.each friends shook hands with each ...
Understanding Handshakes Among Friends
In a gathering of friends, each person shakes hands with every other person exactly once. To calculate the total number of handshakes, we can use a combinatorial approach.
Formula for Handshakes
The number of unique handshakes can be determined using the formula for combinations, specifically choosing 2 friends out of n:
- Total Handshakes = n(n - 1) / 2
Here, n represents the number of friends.
Calculation for 7 Friends
For 7 friends:
- n = 7
Now, substituting into the formula:
- Total Handshakes = 7(7 - 1) / 2
- Total Handshakes = 7 * 6 / 2
- Total Handshakes = 42 / 2
- Total Handshakes = 21
Conclusion
Thus, in a birthday party where 7 friends meet and each shakes hands with every other friend exactly once, there are a total of:
- 21 handshakes.
This formula and method can be applied to any group size to find the total number of unique handshakes, making it a valuable tool in combinatorial counting.
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In a birthday party,7 friends meet.each friends shook hands with each other exactly once.how many shake hands are there?
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