The attenuation (intensity loss) of ultrasound in tissue is approximately -0.3 dB per MHz per cm of depth. (E.g., a 3 MHz signal traveling through 2 cm of tissue has its initial intensity reduced by -0.3x3x2 = -1.8 dB). Approximately how deep into the 1 of its tissue can a 10.5 MHz transducer probe before the intensity is reduced to 2T initial value, where n = 2? Give your answer in centimeters to two significant figures.