Teacher: 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.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Passage: In 1763, Spain traded Florida to the Kingdom of Great Britain for control of Havana, Cuba, which had been captured by the British during the Seven Years' War. It was part of a large expansion of British territory following the country's victory in the Seven Years' War. Almost the entire Spanish population left, taking along most of the remaining indigenous population to Cuba. The British soon constructed the King's Road connecting St. Augustine to Georgia. The road crossed the St. Johns River at a narrow point, which the Seminole called Wacca Pilatka and the British named "Cow Ford", both names ostensibly reflecting the fact that cattle were brought across the river there.
Solution: Who owned Cuba after the Eight Years War?
Reason: This question appears to be relevant to the passage as both involves words such as 'Cuba' and 'War' which also exist in the passage. The passage mentions that "after the war, almost the entire Spanish population left, taking along most of the remaining indigenous population to Cuba". This information is not sufficient to conclude that which country owned cuba.

Now, solve this instance: 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.
Student:
How many Eton students attended Eton free of charge in 2011?