A physical quantity $Q$ is related to four observables $\mathrm{a}, \mathrm{b}, \mathrm{c}, \mathrm{d}$ as follows : $\mathrm{Q}=\frac{\mathrm{ab}}{} \mathrm{a}^{4}$ where, $\mathrm{a}=(60 \pm 3) \mathrm{Pa} ; \mathrm{b}=(20 \pm 0.1) \mathrm{m} ; \mathrm{c}=(40 \pm 0.2) \mathrm{Nsm}^{-2}$ and $\mathrm{d}=(50 \pm 0.1) \mathrm{m}$, then the percentage error in Q is $\frac{x}{1000}$, where $x=$