Algebra
posted by Gianina HELP HELP on .
Each person that works at a company is given a 5digit code followed by a letter,either uppercase or lowercase.These employees must enter their codes on a keypad to enter and exit the office building The company has 130 employees.
a) How many codes are possible if there are no restrictions?
b) What is the probability of someone entering a code at random and gaining entry to building?

there are 10^5 * 52 unique codes
there are 130 valid ones for access
so, it should be clear what p(access) is for random entry. Not high. 
Thank you but I don't understand why is 52 in the first question ;and what is exactly the answer to the question b)