Question

1. Every SIN # (social insurance number) is a sequence of 9 digits. What is the probability of randomly generating 9 digits and getting your own particular SIN number? (Remember that your SIN number cannot begin with a 0. Leave your answer in fractional form).

Answer 1

Social Insurance Number has 9 digits.

The sequence should not begin with 0.

The first number of the sequence is one of the 9 digits. 1,2,3,...9.

There are 9 ways of selecting a number out of 9 numbers.

Then the second number of the sequence is one of the 10 numbers. 0,1,2,3,..,9.

There are 10 ways of selecting a number out of 10.

Similarly for 3rd, 4th,... 9th digits of the sequence, there are 10 ways for selecting the number for each digit.

Overall number of ways of arranging a sequence of 9 digits that does not begin with 0 is 9*10*10*10*10*10*10*10*10= 9*10^8

Each person has unique SIN number.

The probability of randomly generating 9 digits and getting my own particular SIN number = 1/ (9*10^8)

answer is or 1/900000000.

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