Chapter 2 - Section 2.5 - Variation - 2.5 Assess Your Understanding - Page 193: 34

$24$ amperes.

If the current $i$ varies inversely with the resistance $Z$, then there is a nonzero constant $k$ such that $i=\displaystyle \frac{k}{Z}$ --- If $ i=30$ when $Z=8$, substituting, we find k: $30=\displaystyle \frac{k}{8}\quad/\times 8$ $k=240$ Thus, we write: $\displaystyle \quad i=\frac{240}{Z}.$ If $Z=10$, $i=\displaystyle \frac{240}{10}=24$ amperes.