Question

a population of cheetahs has decreased 30% over the last 18 years. if there were originally about 12,000 cheetahs, how many cheetahs are there now?
a. what is the percent decrease in the cheetah population? what was the original population?
b. find the change in the number of cheetahs. write the percent as a decimal.
percent decrease × original amount = decrease amount
____ × __ = ____
c. how many cheetahs are there now?
____ − __ = __, so there are about ____ cheetahs now

Explanation:

Part A

The problem states the population decreased by 30% over 18 years, so the percent decrease is 30%. The original population is given as about 12,000 cheetahs.

Step1: Convert percent to decimal

30% as a decimal is $0.30$ (since to convert a percent to a decimal, we divide by 100, so $30\div100 = 0.30$).

Step2: Multiply by original amount

The original amount is 12,000. So we calculate $0.30\times12000$.
$0.30\times12000 = 3600$

Step1: Identify original and decrease

Original population is 12,000, decrease amount is 3600 (from part B).

Step2: Subtract decrease from original

To find the current population, we do $12000 - 3600$.
$12000 - 3600 = 8400$

Answer:

The percent decrease in the cheetah population is 30%. The original population was 12,000 cheetahs.

Part B