Given the task definition and input, reply with output. In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.

Passage: Born in Sarasota, Florida, Zehr trained from the age of seven with the Sarasota Ballet School and later with the Harid Conservatory in Boca Raton. When she was 17, she joined the Houston Ballet as an apprentice, working with Maina Gielgud there and becoming a soloist in 2006. The National Ballet of Canada in Toronto took her on as a soloist in 2007, promoting her to principal dancer in 2009. In both Houston and Toronto, she established a close personal and professional relationship with Zdenek Konvalina. Following Konvalina, in 2011, she joined the English National Ballet as a principal dancer. She has danced principal roles in several classical ballets including The Sleeping Beauty, Swan Lake and Giselle and in works by George Balanchine such as Apollo (ballet) and Jewels. She received the Rolex Dancers First Award in 2009 for dancing the title role in Davide Bombana's Carmen.
Link Information: Maina Gielgud (born London; 14 January 1945) Answer: 61
How old was Maina Gielgud when Bridgett Zehr became her apprentice?