1. **State the problem:** We need to find how many times taller a piece of lumber is compared to an average human hair. 2. **Given values:** - Height of lumber: $9 \times 10^{1}$ inches - Thickness of hair: $3 \times 10^{-3}$ inches 3. **Formula:** To find how many times taller, divide the height of the lumber by the thickness of the hair: $$\text{Ratio} = \frac{\text{Height of lumber}}{\text{Thickness of hair}}$$ 4. **Substitute the values:** $$\text{Ratio} = \frac{9 \times 10^{1}}{3 \times 10^{-3}}$$ 5. **Simplify the fraction:** $$= \frac{9}{3} \times \frac{10^{1}}{10^{-3}} = 3 \times 10^{1 - (-3)} = 3 \times 10^{4}$$ 6. **Interpretation:** The piece of lumber is $3 \times 10^{4}$ times taller than the human hair. **Final answer:** The lumber is 30000 times taller than the human hair.