A researcher is studying a population with a unique age structure. Over the course of several decades, the histogram that depicts this structure first appears as a pyramid, becomes roughly rectangular in shape, and finally appears as an inverted pyramid (where the base is narrower than the top). How has this population changed over time?

The population first grows, stabilizes, and then declines.

Explanation:

One of the ways to represent data is through the use of histogram. Other ways can be through bar chart and pie chart. In order to draw an histogram to will need to draw bars of different height and each bar means or represent something.

Looking at the question, we were told that the structure of the histogram shows three types of shapes which are;

(1). Pyramid: the pyramid shape shows that the population of that unique age increases.

(2). Rectangular: the rectangular shape depicts that the population of that unique age is at equilibrium.

(3). Inverted pyramid (where the base is narrower than the top): depicts that the population of that unique age has decreased.

world war i had a devastating effect on german-americans and their cultural heritage. up until that point   german-americans, as a group, had been spared much of the discrimination, abuse, rejection, collective mistrust experienced by so many different racial and ethnic groups in the history of the united states. indeed, over the years, they had been viewed as a well integrated and esteemed part of american society. all of this change with the outbreak of war.  

answer; they are called (pebbling);