Probability/Additional Topics in Probability and Counting Question 42 Area Codes

An ares code consists of three digits.  How many area codes are possible if:

  1. there are no restrictions?
    {#1}

  2. the first digit cannot be a 1 or a 0?
    {#2}

  3. What is the probability of selecting an area code at random that ends in an odd number if the first digit cannot be a 1 or a 0.
    {#3}
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