Final answer:
To find the metric measurements of a letter-sized piece of paper, we convert the measurements from inches to centimeters. The metric measurements of a letter-sized piece of paper are approximately 21.6 centimeters by 27.9 centimeters.
Step-by-step explanation:
To measure the length and width of a letter-sized piece of paper in metric units, we can convert the measurements from inches to centimeters. Since the options are millimeters, centimeters, meters, and kilometers, the most appropriate unit of measurement to use would be centimeters. To convert inches to centimeters, we multiply the measurement in inches by 2.54. Therefore, the metric measurements of a letter-sized piece of paper would be approximately 21.6 centimeters by 27.9 centimeters.