Answer
The speed of sound at that temperature is $365~m/s$
Work Step by Step
We can find the speed of sound at that temperature:
$v = (331+0.60~T)~m/s$
$v = [331+(0.60)~(56.7^{\circ}C)]~m/s$
$v = 365~m/s$
The speed of sound at that temperature is $365~m/s$