Maine has 5 letters
Maryland has 8 letters
Massachusetts has 13 letters
Michigan has 8 letters
Minnesota has 9 letters
Mississippi has 11 letters
Missouri has 8 letters
Montana has 7 letters
6 states start with M but are not more than 10 letters long.
They are:
Maine, Maryland, Michigan, Minnesota, Missouri, Montana
The probability is 6 out of 50 or
which reduces to
Edwin