Given the formula below, make 'h' the subject of the formula: A = πr(1 + rh). If A = 250 mm and r = 10 mm, find the value of 'h'.

$$A = \pi r \cdot 1 + \pi r \cdot rh$$ $$A = \pi r + \pi r^2 h$$

$$h = \frac{A - \pi r}{\pi r^2}$$

The subject of the formula is $\boxed{h = \frac{A - \pi r}{\pi r^2}}$.

1.3.2. If $A = 250 \text{ mm}$ and $r = 10 \text{ mm}$, find the value of 'h'.

Using $\pi \approx 3.14159$.

$$h = \frac{250 - 10 \times 3.14159}{100 \times 3.14159}$$ $$h = \frac{250 - 31.4159}{314.159}$$ $$h = \frac{218.5841}{314.159}$$ $$h \approx 0.69579$$

Rounding to three significant figures, the value of $h$ is $\boxed{0.696}$.