Science Question [Environmental Science]?

Question

I feel stupid for not being able to get this..
it's part of a school assignment question.
and who else is better than my fellow yahoo answerians?

An ecologist counted 9 pronghorn antelope in a 4.5-km by 6-km section of prairie. The entire prairie area measured 18 km by 24 km.

Question 1: What was the population density of antelope [per km2 -tiny 2-] in the 4.5-km by 6-km section?

Question 2: Estimatethe total population of pronghorn antelope in the entire prairie area.

Thanks in advance.

Answer 1

Okay let start by finding the area of the observation 4.5(6) is 27 square km. If you divide the number of observed antelope by the total observed area you get 1/3 antelope per square km.

Assuming even distribution of antelope the total prairie is 18(24) or 432 square km which at 1/3 antelope per square km. Divide the area by 3 (same as multiplying by 1/3) gives us 144 antelope.

The previous guy introduced a rounding error by using .33 as an approximation instead of 1/3, so for for every square km he lost .0033333 (you get the idea) antelope which gave him 1.4 less antelope than he should have had but he rounded again so he was only one short.

Answer 2

Try this:

The section is 4.5 * 6 = 27 sq km

So if you have 9 antelope, the density is 9/27 = .33 antelope per sq km

Now the big prairie is 18 * 24 = 432 sq km

So since there's .33 lopes per sq km, .33 * 432 = 143 total antelopes on the big prairie