A scanner receives an ultrasound echo from a tissue boundary 80 μs80\ \mu\mathrm{s}80 μs after sending a pulse. The speed of ultrasound in the tissue is 1540 m/s.
How far below the probe is the boundary?
12.32 cm12.32\ \mathrm{cm}12.32 cm
6.16 cm6.16\ \mathrm{cm}6.16 cm
3.08 cm3.08\ \mathrm{cm}3.08 cm
61.6 cm61.6\ \mathrm{cm}61.6 cm