and a day について

期間（日、月、年）の後に and a day （おまけの一日） がつくと足掛けではなく丸々その期間の長さになる、つまり and a day にはダメ押しの意味がある。ビートルズの歌にEight Days a Week があるが、あれは seven days and a day の意味で月曜の朝から日曜の夜まであの娘に首ったけと言いたいのだろう。101 Dalmatians『101匹わんちゃん』とか、1001 nights, One Thousand and One Nights, Arabian Nights 『千夜一夜物語』などもこの口かもしれない。

https://www.youtube.com/watch?v=y3KEhWTnWvE  0:45 those were the days my friend. we thought they'd never end. we'd sing and dance forever and a day.
Mary Hopkin - Those Were The Days - 1968
https://www.youtube.com/watch?v=H9WCdpL2T-o  0:33 now the phrase 'bring home the bacon' comes from the 12th century when an England church offered a side of bacon to any man who could swear before God and the congregation that he had not fought or quarreled with his wife for a year and a day. 丸一年
Toni On! New York: The History Behind Porky Goodness

参考リンク
http://bridge-english.blogspot.com/2017/12/one-and-all-everyone.html   one and all = everyone

練習問題解答
a-1966 a year and a day
a-3482 40 years and one day
a-8771 forever and a day
b-1625 one year and one day
b-3429 two months and a day 多分、まるまる二ヶ月の意味だと思うが、二ヶ月と一日の意味も排除できない。