Extra Exercise 12
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Some possible explanations:

* a P-value below 1% (i.e., significance at 1%) is also below 5% (i.e., significance at 5%),

* an event occurring by chance with probability less than 1% also occurs with probability less than 5%,

* it is "more difficult" (in the sense of a stronger requirement) to be significant at the 1% than 5% level.