If y(x,t) = (6.4 mm) sin[kx + (930 rad/s)t + φ] describes a wave traveling along…

If
y(x,t) = (6.4 mm) sin[kx + (930 rad/s)t
+ φ]
describes a wave traveling along a string, how much time does any
given point on the string take to move between displacements
y = +1.0 mm and y = -1.0 mm?