[填空题]
An unfingered guitar string is 0.73 m long and/h:n) (hlmkmm is 5mkrs:5+*g2lct ao cctuned to play E above middle C (330aco 5lkr s5gm*2:t+cc Hz).
(a) How far from the end of this string must the finger be placed to play A above middle C (440 Hz)?$\approx$ m
(b) What is the wavelength on the string of this 440-Hz wave? $\approx$ m
(c) What are the frequency and wavelength of the sound wave produced in air at 20°C by this fingered string? Hz m