Question

The width of a human hair is about 1 * 10^(-4) meter wide. The width of mechanical pencil lead is about 7 * 10^(-4) meter wide. About how many pieces of hair would it take to match the width of a piece of mechanical pencil lead?

A) 7
B) 70
C) 10
D) 100

Answer 1

To match the width of a piece of mechanical pencil lead with human hair, it would take 7 pieces of human hair since the width of pencil lead is 7 times that of human hair.

Step-by-step explanation:

The question asks how many pieces of hair are needed to match the width of a piece of mechanical pencil lead. Given that the width of a human hair is about 1 × 10(-4) meter and the width of mechanical pencil lead is about 7 × 10(-4) meter, we calculate the ratio of the width of the pencil lead to the width of a human hair to find out how many hairs would match the width of the lead.

To find this ratio, we divide the width of the pencil lead by the width of human hair:

7 × 10(-4) meter ÷ 1 × 10(-4) meter = 7

Thus, it would take 7 pieces of human hair to match the width of a piece of mechanical pencil lead. Therefore, the correct answer is A) 7.