Nobody can Imagine a world without sound. Sound is a part of our life- musics, ripples, echoes etc. have a lot of applications. Can you say how a bat can ascertain directions and distances without any 'eyes'?

Nobody can Imagine a world without sound. Sound is a part of our life- musics, ripples, echoes etc. have a lot of applications.Doctors use an ultrasonic scanner to diagnose tumour tissues. If the frequency of the scanner is locate 4.2MHz and the speed of sound wave in the tissue of is 1.7 kms find the wavelength of the sound wave.

Without multiplying can you say how many decimal places will it have in (1.5)^3 .