Question 19 of 497

A student measures the thickness of a human hair by looking at it through a microscope of magnification 100. He makes 20 observations and finds that the average width of the hair is 3.5 mm. What is the estimate on the thickness of the hair? (a) 0.0035 mm (c) 0.01 nm b) 0.035 mm (d) 0.7 mm