This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: The first extant Estonian book is a bilingual German-Estonian translation of the Lutheran catechism by S. Wanradt and J. Koell dating to 1535, during the Protestant Reformation period. An Estonian grammar book to be used by priests was printed in German in 1637. The New Testament was translated into southern Estonian in 1686 (northern Estonian, 1715). The two languages were united based on northern Estonian by Anton thor Helle.
Who wrote the last Estonian book? 

Passage: During the year following that contract, with Dodsley, Burke founded the influential Annual Register, a publication in which various authors evaluated the international political events of the previous year. The extent to which Burke contributed to the Annual Register is unclear: in his biography of Burke, Robert Murray quotes the Register as evidence of Burke's opinions, yet Philip Magnus in his biography does not cite it directly as a reference. Burke remained the chief editor of the publication until at least 1789 and there is no evidence that any other writer contributed to it before 1766.
What was founded the year before the contract?

Passage: About 20% of pupils at Eton receive financial support, through a range of bursaries and scholarships. The recent Head Master, Tony Little, said that Eton is developing plans to allow any boy to attend the school whatever his parents' income and, in 2011, said that around 250 boys received "significant" financial help from the school. In early 2014, this figure had risen to 263 pupils receiving the equivalent of around 60% of school fee assistance, whilst a further 63 received their education free of charge. Little said that, in the short term, he wanted to ensure that around 320 pupils per year receive bursaries, and that 70 were educated free of charge, with the intention that the number of pupils receiving financial assistance would continue to increase. These comparatively new developments will run alongside long-established courses that Eton has provided for pupils from state schools, most of them in the summer holidays (July and August). Launched in 1982, the Universities Summer School is an intensive residential course open to boys and girls throughout the UK who attend state schools, are at the end of their first year in the Sixth Form, and are about to begin their final year of schooling. The Brent-Eton Summer School, started in 1994, offers 40-50 young people from the London Borough of Brent, an area of inner-city deprivation, an intensive one-week residential course, free of charge, designed to help bridge the gap between GCSE and A-level. In 2008, Eton helped found the Eton, Slough, Windsor and Hounslow Independent and State School Partnership (ISSP), with six local state schools. The ISSP's aims are "to raise pupil achievement, improve pupil self-esteem, raise pupil aspirations and improve professional practice across the schools". Eton also runs a number of choral and English language courses during the summer months.

How many Eton students attended Eton free of charge in 2011?