b. In 1979, the estimated elephant population was 1.3 million and in 2007 it was 640,000. By approximately what percentage did the elephant population decline over this time period? (Show your work.) How does this compare to the change in range over this same time period?

In order to calculate the percentage decline over the period of time between 1979 and 2007, the general formula for percentage change will be applied. This is as follows:

where:

A = final value

B = initial value

In this problem:

A = Initial population = 1,300,000

B = Final population = 640,000

Applying this formula to the problem, the percentage change in population between 1979 and 2007 is as follows:

B: The change in range over this period of time is the difference between the final population and the initial populations, which is calcalated thus:

B - A (as explained above)

= 640,000 - 1,300,000 = - 660,000 (the minus sign still shows a decline)

While the percentage shows a "relative change" in terms of percentage, the change in range shows an absolute or actual change.

A similar example might help you understand more, check it out here: link

The initial amount, 1.3 million = 1,300,000 is the 100%.

now, 640,000 is a given percentage (lower than 100%) of that.

How we can find it?

suppose that 640,000 represents an x%.

Then we have that the quotient between the actual quantities and the percentages must be the same

(640,000/1,300,000) = x%/100%

x% = (640,000/1,300,000)*100% = 49.23%

Then the percentage declined is:

100% - 49.23% = 50.77%

The other question can not be answered with the given information.