Answer
$\lambda=371.2nm$
Work Step by Step
We can find the wavelength as follows:
$\frac{1}{\lambda}=(R)(\frac{1}{2^2}-\frac{1}{n^2})$
We plug in the known values to obtain:
$\frac{1}{\lambda}=(1.097\times 10^7)(\frac{1}{2^2}-\frac{1}{15^2})$
Solving for $\lambda$:
$\lambda=371.2nm$