College Physics (7th Edition)

$I_{1}=\frac{q_{1}}{t_{1}}=\frac{20\,C}{1.25\times60\,s}=0.27\,A$ Given: $q_{2}=30\,C,$ $I_{2}=2I_{1}=2\times0.27\,A=0.54\,A$ Therefore, $t_{2}=\frac{q_{2}}{I_{2}}=\frac{30\,C}{0.54\,A}=56\,s$