Final answer:
The correct measurement of a penny using a ruler with 2 mm increments is 17.2 mm, as it's the closest measurement that can be determined with certainty given the ruler's degree of precision.
Step-by-step explanation:
The given ruler has markings every 2 mm and is used to measure the size of a penny. Given the options of 17.18 mm, 17.2 mm, and 17 mm, the correct measurement that can be reported by this ruler is 17.2 mm. Since the ruler only marks every 2 mm (which is equivalent to 0.2 cm), it cannot measure to the hundredths place (which would be required to report 17.18 mm).
Thus, the measurement should be rounded to the nearest 2 mm or 0.2 cm, making 17.2 mm the most accurate report.
It's essential to report measurements to the correct degree of precision, which is determined by the smallest division on the measuring tool being used. In this case, the 2 mm (or 0.2 cm) markings provide a level of precision that allows you to confidently report the first digit after the decimal in centimeters, making any hundredths estimation uncertain and not reportable.