The sum of the absolute frequencies is equal to the total number of data, represented bas $$N$$. 1  Relative frequency: the result of dividing the absolute frequency of a certain value by the total number of data.  The sum of the relative frequencies is equal to $$1$$. We can prove this easily by factorizing $$N$$.
Periodical cicadas emerge from underground every 13 or 17 years, depending upon which brood the cicadas belong to. The year a particular brood emerges often differs from other broods and is also dependent on geography. The periodical cicada, although unrelated, is often mistakenly called a locust.
Most of the complex spatial and temporal relationships of periodical cicada broods and species must be less than 10,000 years old, because much of the current range of periodical cicadas in the eastern, Appalachian, and Midwestern U.S. would have been unsuitable for periodical cicadas during and for substantial periods following the Wisconsin ...