A wooden plant accumulates $10 𝑚𝑔 𝑘𝑔^{−1}$ of $^{14}C$ during its life span. A fossil of this plant was discovered and contains $2.5 𝑚𝑔 𝑘𝑔^{−1}$ of $^{14}C$. The age of this fossil at the time of discovery is years (rounded off to the nearest integer).
(Use 5730 years as half-life of $^{14}C$)