It is exponential growth because it says 18.36% "more than" and it can be linear because it does not stay at a constant rate of change. Answer: Exponential growth
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The answer would be the third one, p<319, because the auditorium can seat AT LEAST (<) 320 people, but it would be preferable to contain 319.
50:
40 is 10 less than 50
60 is 10 more than 50