An air-core radio-frequency transformer as shown has a primary winding and a secondary winding. The mutual inductance $M$ between the windings of the transformer is $\_\_\_\_$ $\mu \mathrm{H}$. (Round off to 2 decimal places)

The current i (in Ampere) in the 2 Ω resistor of the given network is _________.

In the given circuit, the parameter k is positive, and the power dissipated in the 2 Ω resistor is 12.5 W. The value of k is ________.

An incandescent lamp is marked 40W, 240V. If resistance at room temperature $$\left(26^\circ\mathrm C\right)\;\mathrm{is}\;120\mathrm\Omega$$ and temperature coefficient of resistance is $$4.5\;\times\;10^{-3}/^\circ C$$ , then its ‘ON’ state filament temperature in ^oC is approximately ________.