I=870π 2 a 2 f 2 I, equals, 870, pi, squared, a, squared, f, squared The intensity, III, of a sound wave is defined as its power output per unit area and is measured in watts per square meter \left( \dfrac{\text W}{\text m^2} \right)( m 2 W )left parenthesis, start fraction, start text, W, end text, divided by, start text, m, end text, squared, end fraction, right parenthesis. A sound wave's intensity can be calculated using the above equation, where aaa stands for the wave's amplitude in meters (\text m)(m)left parenthesis, start text, m, end text, right parenthesis and fff stands for its frequency of vibration in hertz (\text{Hz})(Hz)left parenthesis, start text, H, z, end text, right parenthesis. If a particular sound wave has an intensity of 0.05 \, \dfrac{\text W}{\text m^2}0.05 m 2 W 0, point, 05, start fraction, start text, W, end text, divided by, start text, m, end text, squared, end fraction and an amplitude of 3 \times 10^{-5} \, \text{m}3×10 −5 m3, times, 10, start superscript, minus, 5, end superscript, start text, m, end text, which of the following is most nearly its frequency?