The equation of a wave traveling in a horizontal direction is expressed as y = 15 sin 2π5 (60t - x). What is its wavelength?

The general equation for a sinusoidal wave traveling in the positive x-direction is given by:

where $A$ is the amplitude, $\omega$ is the angular frequency, and $k$ is the wave number.

The given equation is $y = 15 \sin \left(2\pi \cdot 5 (60t - x)\right)$.
First, distribute the $2\pi \cdot 5$ term inside the parenthesis:

By comparing $y = 15 \sin \left( 600\pi t - 10\pi x \right)$ with $y = A \sin(\omega t - kx)$, we can identify:
$\omega = 600\pi$
$k = 10\pi$

The relationship between the wave number $k$ and the wavelength $\lambda$ is:

Substitute the value of $k$ we found:

Divide both sides by $2\pi$:

The wavelength of the wave is 0.2 units.

The final answer is 0.2.