<image>During the Spring Festival travel season, a station conducted a random survey of 100 passengers to understand the ticket purchase situation. The survey measured the time \( t \) (referred to as ticket purchase time, in minutes) taken from the start of lining up at the ticket window to obtaining the ticket. Below is the frequency distribution table and frequency distribution histogram resulting from the statistical analysis of this survey (as shown in the figure).
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Answer the following questions:
(1) What is the sample size of this survey?
(2) Fill in the missing data in the table and complete the frequency distribution histogram;
(3) In which group is the mean ticket purchase time of passengers likely to fall?