From the information given, a right-tailed test using the z-distribution is appropriate.
At the null hypothesis, it is tested if the class of statistics students is not significantly smarter than the general population, that is, their mean IQ is of at most 100, hence:
[tex]H_0: \mu \leq 100[/tex]
At the alternative hypothesis, it is tested if they are significantly smarter, that is, their mean IQ is greater than 100, hence:
[tex]H_1: \mu > 100[/tex]
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