A narrow walkway is paved with \(80\) identical square stones. Each stone has side length \(30\,\text{cm}\), and the stones are laid with no gaps or cuts.
a) The finished walkway is exactly \(1.20\,\text{m}\) wide. How long is it?
b) The walkway will be extended by \(1.50\,\text{m}\) while keeping the same width. How many additional stones are needed?
Hints
- Determine how many stones fit across the \(1.20\,\text{m}\) width.
- Use the number of stones in each row to find how many rows the original walkway has.
- For part b), find how many new rows fit in \(1.50\,\text{m}\).
Solution
1. Each stone is \(0.30\,\text{m}\) wide, so the number of stones across the walkway is \(1.20\div0.30=4\).
2. The \(80\) stones make \(80\div4=20\) rows along the walkway. Its length is \(20\times0.30=6\,\text{m}\).
3. Extending the walkway by \(1.50\,\text{m}\) requires \(1.50\div0.30=5\) more rows.
4. Each row uses \(4\) stones, so the extension requires \(5\times4=20\) additional stones.
Answer
a) The walkway is \(6\,\text{m}\) long.
b) The extension requires \(20\) additional stones.