\[1)\ 60\ 000 + \frac{p}{100} \cdot 60\ 000 =\]
\[= 60\ 000 + 600p\ (р) -\]
\[к\ концу\ 1\ года.\]
\[6p² + 1212p - 4944 = 0\ \ \ |\ :6\]
\[p^{2} + 202p - 824 = 0\]
\[D = 40\ 804 + 3296 = 44\ 100\]
\[p_{1} = \frac{- 202 + 210}{2} = 4;\ \ \ \]
\[Ответ:4\%.\ \]