SOLUTION: The student number at a University consists of 2 letters, followed by 4 digits, followed by 2 letters. How many different student numbers are possible if: a. Letters and digits c

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Question 322420: The student number at a University consists of 2 letters, followed by 4 digits, followed by 2 letters. How many different student numbers are possible if:
a. Letters and digits cannot be repeated.
b. Letters can be repeated, but digits cannot.
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


a. There are 26 ways to select the first letter, then 25 ways to select the 2nd letter, then 24 ways to select the 3rd letter and 23 ways to select the 4th letter. There are 10 ways to select the first digit, 9 ways to select the second digit...and so on.



b. Since you can repeat letters, the calculation changes to:



You get to do your own arithmetic.


John