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MathNet 2009-part-03 — 175 problems (EN–VI) Question 143

Math Olympiad Vault · MathNet 2009-part-03 — 175 problems (EN–VI)

Question 143

On 11 sheets of paper 11 following statements are written (each sheet contains exactly one statement):
1) There are no sheets with false statements to the left of this sheet.
2) There is exactly 1 sheet with a false statement to the left of this sheet.
3) There are exactly 2 sheets with false statements to the left of this sheet.
...
11) There are exactly 10 sheets with false statements to the left of this sheet.

The sheets were put in a row (from the left to the right). After that some of the statements become true while the others become false. Find the greatest possible number of true statements.