What measurement increments should rulers and graduated cylinders use to read to one-tenth units?

• A. Two-tenths
• B. One-tenth units
• C. Whole units only
• D. Hundredths

Answer: (B)

To read to the nearest tenth, the tool must be marked in tenths of a unit. The smallest division on the scale determines how precisely you can measure. If the scale only has marks every 0.2 unit, you can’t reliably report a measurement to the tenths place because there’s no mark to guide you between the larger intervals. If it’s marked only in whole units, tenths are impossible to determine. A scale with hundredth marks would let you be even more precise, but that level of detail isn’t necessary for reading to a tenth and isn’t required for this level of measurement. Therefore, using one-tenth unit markings lets you read and report measurements to the nearest tenth accurately, since you can align with the mark for the tenths and make a reasonable estimate for the digit between marks.