Transverse waves on a string have wave speed 8.00 m/s, amplitude 0.0700 m and wavelength 0.320m. The waves travel in the -x direction, and at t=0 the x=0 end of the string has its maximum upward displacement. (a) Find the frequency, period, and wave number of these waves. (b) Write a wave function describing the wave. (c) Find the transverse displacement of a particle at x = 0.360 m at time t = 0.150 s. (d) How much time must elapse fromust elapse from the instant in part (c) until the particle at x=0.360 m next has maximum upward displacement?
a) f = 25 Hz, T = 0.04s, k = 25π/4 rad/m
b)y(x,t) = 0.07cos2π(25t + 25x/8)

c) +0.0495m

I am not sure how to answer part d and I keep getting the wrong answer... any help would be appreciated.