Final answer:
The width of a human hair is about 6.5 · 10⁻⁵ meters, and this is already in scientific notation. To express this in micrometers, we find it is equivalent to 65 μm.
Step-by-step explanation:
The width of a human hair is given as about 6.5 · 10-5 meters. This width is already written in scientific notation. However, to express this width in terms of micrometers (μm), which are more commonly used to measure such small dimensions, we convert the measurement by realizing that 1 μm equals 10-6 meters. Therefore, we can rewrite the width of the hair as 65 · 10-6 meters or 65 μm, as 6.5 · 10-5 meters is equivalent to 65 · 10-6 meters.