When a die is tossed thrice, the sample space is
S = {(x, y, z) : x, y, z ∈{1, 2, 3, 4, 5, 6}}, which contains 6 × 6 × 6 = 216 equally likely events.
Let E : ‘an odd number atleast once’ then, Ec : ‘not an odd number at any time’ i.e., Ec = ‘an even number on all throws'
or Ec = {(x, y, z) : x, y, z ∈ {2, 4, 6}}
⇒ Ec contains 3 × 3 × 3 = 27 equally likely simple events.
⇒P(Ec)=

27

216

∴ Required probability =P(E)=1−P(Ec) =1−

27

216

=

7

8

.