The correct option (a) (2n/5n)
Explanation:
Last digit can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
∴ Number of ways of choosing last digit = 10n
given: last digit be 1, 3, 7, 9. (none of it is even or 0 or 5)
we have choice of 4 digit i.e. 1, 3, 7, 9 with each n numbers should end.
∴ favourable number of ways = 4n
∴ probability = (4n/10n) = (2/5)n.