One way to determine the density of animals in an area is to use the mark-recapture technique. A number of individuals from a population are captured, marked so they are easily identifiable, and released back into the population. It's assumed that the captured and marked animals will randomly mingle with the rest of the population. Later, the population is re-sampled and the number of marked and unmarked animals is recorded. The following equation can then be used to estimate the size of the entire population. Number of individual marked in first catch/Total population size, N = Number of individual marked in 2nd catch / Total number of 2nd catch

If 25 Prairie Dogs were captured, marked, and released back into their population, and then subsequently 135 Prairie Dogs were captured, of which 18 were marked, what is the approximate total population size, N?

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.