The new number, 200, is 400 less than the original number. What is the approximate percent change?
Answer: alternative D.
Explanation: Dr. DeVries should choose his sample population randomly in order for his research to be representative, even having a specific population, which is high school seniors, that he wants to study. By <u>choosing specifically students from an exclusive college preparatory school, he isn't considering how students from other schools might perform in his research test</u>. This would be a very important step for him to understand how the practice in problem solving affects the ability related to it. Otherwise, he will have a distorted result.
The answer is 1950-2000, China reached 1 billion people in population in 1982.
