GMATprep 1 ps problem 1

[gmatjoe]

Hi there, Could anyone kindly explain me how to solve this problem?

Many thanks in advance, Joe.

[ikant]

Hi,

Here is the soln the answer is 27(26)^4.

No. of 4 letter codes formed = (26)^4.

No. of 5 letter codes formed = (26)^5.

So total no. of codes = (26)^4(1+26)
= 27(26)^4.

[gmatjoe]

many thanks.