(1) According to the meaning of the question, combining the fan chart and the bar chart, 540 people participated in the first grade of high school, accounting for 45%, and ***540÷45%=1200 people,
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Furthermore, we can get that the third year of high school has 240÷1200×100%=20%,
the second year of high school accounts for 1-45%-20%=35%;
So the answer It is 1200, 35%, 20%.
(2)
(3) There are 1 first prize, 3 second prizes, 6 third prizes, and m commemorative prizes,
< p> Then: 103×520×6+m?2=5702m=200
m=100
∴This event The probability of winning is: 1+3+6+100 1200 = 110 1200 = 11 120 (10 points)