Previous Year Paper
CAT-2002-Previous Years Paper
Each of the 11 letters A, H, I, M, O, T, U, V, W, X and Z appears same when looked at in a mirror. They are called symmetric letters. Other letters in the alphabet are asymmetric letters.
How many three-letter computer passwords can be formed (no repetition allowed) with at least one symmetric letter?
A 990 B 2,730
C 12,870 D 15.600
Total number of passwords using all letters – Total number of passwords using no symmetric letters = (26 × 25 × 24) – (15 × 14 × 13) = 12870