A torque meter is calibrated to reference standards of mass, length and time each with $$5\%$$ accuracy. After calibration, the measured torque with this torque meter will have net accuracy of

We need to find the net accuracy of torque measured by a torque meter calibrated with 5% accuracy in mass, length, and time.

The dimensional formula of torque is derived from torque = force $$\times$$ distance = (mass $$\times$$ acceleration) $$\times$$ distance, which yields $$\tau = M L^2 T^{-2}$$.

For a quantity $$\tau = M^a L^b T^c$$, the maximum percentage error is given by $$\frac{\Delta \tau}{\tau} \times 100 = a\left(\frac{\Delta M}{M}\right) \times 100 + b\left(\frac{\Delta L}{L}\right) \times 100 + |c|\left(\frac{\Delta T}{T}\right) \times 100$$.

Here $$a = 1$$, $$b = 2$$, $$|c| = 2$$, and each accuracy is $$5\%$$, so $$\frac{\Delta \tau}{\tau} \times 100 = 1 \times 5\% + 2 \times 5\% + 2 \times 5\% = 5\% + 10\% + 10\% = 25\%$$.

The correct answer is Option B: $$25\%$$.