Quantitative Aptitude Ques 2173
Question: If ten friends shake hands mutually, then the total number of handshakes is
Options:
A) 45
B) 50
C) 90
D) 100
Show Answer
Answer:
Correct Answer: A
Solution:
- It is to be noted that, when two persons shake hands, it is counted as one handshake.
$ \therefore $ Total number of handshakes $ ={}^{10}C _2 $ $ \because $ $ {}^{n}C _{r}=\frac{n!}{r!(n-r)!}=\frac{10!}{2!(10-2)!} $ $ =\frac{10\times 9\times 8!}{2\times 1\times 8!}=\frac{10\times 9}{2}=45 $
BETA
