Trying to find information on Anna Anderson

I trying to find out some information on an ancestor named Anna Anderson. I don't know when she was born so that is what I want to try to find out. She was born to Sivert and Marie Anderson. Sivert was born: April 29, 1835 and died: September 18, 1893 in America. Marie was born: March 24, 1834 and died: July 05, 1920 in America. Sivert's parents were Anders and Beret Klukken. Anna's youngest siblings were born in 1879 and 1880 so she would be older than them. She was most likely born in Norway. Any info would be greatly appreciated!