Show that |Bn| ≤ 2n/4 by defining a one-to-one function g : {0, 1} n/4 → Bn and using the Mapping Rule. (Hint: consider [][] and [[]].) How many passwords can be made from any 15 (uppercase-only)...

Show that |B_n| ≤ 2^n/4
by defining a one-to-one function g : {0, 1} n/4 → B_n
and using the Mapping Rule. (Hint: consider [][] and [[]].)

How many passwords can be made from any 15 (uppercase-only) letters? How many passwords can be made by pasting together three 5-letter words from this dictionary?