What vocal and instrumental duo consisting of siblings Karen (1950-1983) and Richard Carpenter (b. 1946) covered Tim Hardin's "Reason to Believe"?
Tim Hardin:  He wrote the Top 40 hit "If I Were a Carpenter", covered by, among others, Bobby Darin, Joan Baez, Johnny Cash, The Four Tops, Robert Plant, and Johnny Rivers; his song "Reason to Believe" has also been covered by many artists, notably Rod Stewart (who had a chart hit with the song), Neil Young, and The Carpenters. The Carpenters: The Carpenters were an American vocal and instrumental duo consisting of siblings Karen (1950-1983) and Richard Carpenter (b. 1946).
The Carpenters