A certain stock exchange designates each stock with one, two or three letter code, where each letter is selected from 26 letters of the alphabet. If the letters maybe repeated and if the same letters used in different order constitute different code, how many different stocks is it possible to uniquely designate with these code.
a) 2951
b) 8125
c) 15600
d) 16302
e) 18278
I was not able to solve. Can someone please help. I will post OA soon.
Thanks.
Combinatorics problem from GMATPREP
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one letter code: 26 = 26 codes
two letter code 26 x 26 = 676 codes
three letter code 26 x 26 x 26 = 17576 codes
total number of codes = 26 + 676 + 17576 = 18278...
two letter code 26 x 26 = 676 codes
three letter code 26 x 26 x 26 = 17576 codes
total number of codes = 26 + 676 + 17576 = 18278...