Wednesday.
You can find a day of week calculator at this site. Just enter in the date and it will calculate it for you:
http://www.searchforancestors.com/utility/dayofweek.html
10 October 1984 was a Wednesday.
October 19th, 1984 was a Friday.
October 26, 1984 was a Friday.
October 11th, 1984 fell on a Thursday.
October 7th 1984 was a Sunday.
October 4 1984 was a Thursday.
October 6 1984 was a Saturday.
October 8, 1984 was a Monday.
October 12 1984 was a Friday.
October 27, 1984 was a Saturday.
October 15, 1984 fell on a Monday.
October 9, 1984 fell on a Tuesday.