A boy measures the thickness of a human hair by looking at it through a microscope of magnification 100x. After 25 observations, the boy finds that the average width of the hair in the field of view of the microscope is 3.8 mm. What is the estimate on the thickness of hair?

Explanation

To find the estimated thickness of a human hair using the data provided, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Magnification**: The microscope has a magnification of 100x. This means that the image of the hair appears 100 times larger than its actual size.

2. **Average Width in the Microscope**: The average width of the hair observed through the microscope is given as 3.8 mm. This measurement is not the actual thickness of the hair but rather the thickness as seen through the microscope.

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