Answer:
The answer is 0.009.
Explanation:
The total number of people from which only 9 earned a perfect score = 1,000.
The number of people who earned a perfect score = 9
The decimal that represents the number of people who earned a perfect score = The number of people who earned a perfect score ÷ The total number of people concerned = 9 ÷ 1,000 = 0.009.