probability: fraction of sequences with property that....

[lunabee]

A sequence of length 7 is formed form the digits 0,1,....9. Each digit can be used as odten as you like. What fraction of these sequences.
a. begins with 1?

 

[tkhunny]

You haven't defined how the digits are chosen (uniformly random?), or if there are any rules (can't start with zero).

If they are uniformly random, and can start with anything, how about 1/10?