NDA Math Probability Part 2

Number of ways in which one of the face having the number 6 and no two dice show the same number.
(1,2,6),(1,3,6),(1,4,6),(1,5,6),(2,3,6),(2,4,6),(2,5,6),(3,4,6),(3,5,6).....
Total favourable case =20+20+20=60.
Number of total output when three top faces of three dice shows different number =6×5×4=120.
∴ Required probability =

60

120

=

1

2