Question

a hospital uses an ultrasonic scanner to locate tumours in a tissue what is the wavelength of ultrasound if speed =1.5km/s and frequency=4mHz

Answer 1

we have to find wavelength please see the attachment

Answer 2

v = 1.5 km/s = 1500 m/s
f = 4 MHz = 4×10⁶ Hz

$speed=frequency \times wavelength\\ \\v=f \times \lambda\\ \\ \lambda= \frac{v}{f} = \frac{1500}{4 \times 10^6} =\boxed{3.75 \times 10^{-4}\ m}$