Interview Q&A / Aptitude

1. In how many ways can 6 people sit around a round table? In how many of these do two particular friends sit together?

   120 ways in total, since circular arrangements of n people number (n - 1)! = 5! = 120. With two friends together, treat them as one unit: (5 - 1)! x 2 = 24 x 2 = 48 ways.

   IntermediateQuick answer1 min read
2. In how many ways can the letters of LEADER be arranged so that the vowels always come together?

   72. Treat the vowels E, A, E as one block. The block plus L, D, R makes 4 units, arranged in 4! = 24 ways. Inside the block, E, A, E arrange in 3!/2! = 3 ways. Total 24 x 3 = 72.

   IntermediateQuick answer1 min read