An optical fibre has an attenuation of 0.3 dB/km. If a laser launches an optical power level of PIN (mW) into 35 km length of this fibre, at what distances will the power have dropped to:

(a) 75%

(b) 50%

(c) 25%

(d) 12.5%

(e) 6.25%

of the input power level? Plot these points on a graph of P IN/P OUT versus distance along the fibre.