Answer
$T = 2180~N$
Work Step by Step
We can find the speed of the wave along the wire.
$v = f~\lambda$
$v = (f)~(2L_{vib})$
$v = (27.5~Hz)(2)(1.90~m)$
$v = 104.5~m/s$
We can find the tension in the wire.
$v = \sqrt{\frac{T}{\mu}}$
$v = \sqrt{\frac{T}{m/L}}$
$T = \frac{v^2~m}{L}$
$T = \frac{(104.5~m/s)^2(0.400~kg)}{2.00~m}$
$T = 2180~N$
