Round table selection
Probability
Level
2
There are 12 persons sitting around a circular table. Then the number of ways of selecting 3 persons out of them such that no two persons are adjacent to each other.
220
108
112
124
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1 solution
Total number of ways of selecting 3 out of 12 is 12C3=220. The nos which are together are taken into consideration= (1,2,3),(2,3,4)....(11,12,1),(12,1,2) overall 12 ways this can b done! now two are together and one is away, it can b done in 12 x 8=96 ways. So required arrangements=220-12-96=112.