Answer: 0.0476
Step-by-step explanation:
Given : Two friends and 5 other people compete with each other for first and second chair in an orchestra.
Total people in this competition= 2+5=7
By permutation , Number of ways to arrange 7 people= 7!
Also, number of ways for two friends end up as first and second chair together= 2 × 5! [ 2 ways to arrange friends on first and second chair and 5! ways to arrange others]
I.e. Required probability = [tex]\dfrac{2\times5!}{7!}[/tex]
[tex]=\dfrac{2!\times5!}{7\times6\times5!}\\\\=\dfrac{1}{7\times3}\\\\=\dfrac{1}{21}\\\\=0.0476[/tex]
Hence, the probability that the two friends end up as first and second chair together = 0.0476
