Final answer:
An approximate estimate for the diameter of a speck of dust, which is about 0.00002 inches, would be about 0.5 micrometers. This size is minuscule, notably smaller than a grain of sand or the thickness of a human hair.
Step-by-step explanation:
The student asked for an appropriate estimate for the diameter of a speck of dust, which is about 0.00002 inches. To estimate this diameter, we can compare it to known sizes or use a metric conversion to understand the size better. The size is smaller than a grain of sand and much smaller than the thickness of a human hair, which is typically around 0.003 inches. Converting inches to millimeters, 1 inch is approximately 25.4 millimeters. Therefore, 0.00002 inches is about 0.000508 millimeters, which we can round up to about 0.0005 millimeters or 0.5 micrometers. This estimate fits within the size range of dust particles.