An ultrasound transducer is used to image a boundary between muscle tissue and a deeper biological medium. The acoustic impedance of the muscle tissue is Z1=1.70×106 kg m−2 s−1Z_1 = 1.70 \times 10^6 \text{ kg m}^{-2}\text{ s}^{-1}Z1=1.70×106 kg m−2 s−1. At the boundary, 4.00% of the incident ultrasound intensity is reflected back towards the transducer. Assuming normal incidence, which of the following is a possible value for the acoustic impedance, Z2Z_2Z2, of the deeper biological medium?
1.36×106 kg m−2 s−11.36 \times 10^6 \text{ kg m}^{-2}\text{ s}^{-1}1.36×106 kg m−2 s−1
1.84×106 kg m−2 s−11.84 \times 10^6 \text{ kg m}^{-2}\text{ s}^{-1}1.84×106 kg m−2 s−1
2.04×106 kg m−2 s−12.04 \times 10^6 \text{ kg m}^{-2}\text{ s}^{-1}2.04×106 kg m−2 s−1
2.55×106 kg m−2 s−12.55 \times 10^6 \text{ kg m}^{-2}\text{ s}^{-1}2.55×106 kg m−2 s−1
