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Post time 2017-10-30 12:22:40 |Show the author posts only |Descending
Dear players,
Forum Event " The Interesting Math Question Can Relax You! " from Oct.27th to Oct.29th has ended. Thanks for your active participation and answers. Now, we announce the answer and winners. If any other players answer the question correctly, but you aren't on the following list. Please contact  us in forum and write your right ign and server. Congratulations!
Answer:
Let x be the number of correct answers
Let y be the number of wrong answers
Unanswered questions will be 25 - x - y
2x + y (-1) + 0(25 - x - y) = 34
2x - y = 34
y = 2x - 34
So we can know 2x - 34 can be bigger or equal to 0, and x + y can be smaller or equal to 25
so 2x - 34 ≥ 0 and we also know x+y ≤ 25
2x ≥ 34
x ≥ 34/2, thus x ≥ 17
Since unanswered questions is a odd number, using the following probabilities
1. y = 2 (17) - 34 = 0, thus unanswered questions will be 25 - 17 - 0 = 8 (ruled out)
2. y = 2 (18) - 34 = 2, thus unanswered questions will be 25 - 18 - 2 = 5 (correct possibility)
3. y = 2 (19) - 34 = 4, thus unanswered questions will be 25 - 19 - 4 = 2 (ruled out)
4. y = 2 (20) - 34 = 6, thus unanswered questions will be 25 - 20 - 6 = -1 (ruled out)
Thus the questions answered correctly is 18, questions answered incorrectly is 2, and unanswered questions is 5
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