The answer is friday!
According to www.timeanddate.com, March 1, 1971 was a Monday.
March 13, 1971, was a Saturday.
March 11th 1971 was on a Thursday.
March 15 1971 was a Monday.
March 8 1971 was a Monday.
March 18 1971 was a Thursday.
March 31, 1971 fell on a Wednesday.
March 5, 1971 fell on a Friday.
March 27, 1971 fell on a Saturday.
March 26, 1971 fell on a Friday.
March 10, 1971 fell on a Wednesday.
Saturday