What Could Be Wrong with My Wave Function Equation?

[lina29]

A simple, harmonic oscillator at the point x=0 generates a wave on a rope. The oscillator operates at a frequency of 40 Hz and with an amplitude of 3.00 cm. The rope has a linear mass density of 50.0 g/m and is stretched with a tension of 4.50 N.

Write the wave function y(x,t) for the wave moving in +x-direction. Assume that the oscillator has its maximum upward displacement at time t=0.

I know to write the wave function I use the equation y(x,t)=Acos(kx-wt)
where A=3, k=2pi/$$\lambda$$=8pi, w=2pif=80pi

So I got the equation y(x,t)=3cos(8pi x-80pi t)

However when I put it in it says the equation is wrong

Can anyone help me in figuring out what I missed?
Thanks

 

[zorro]

How did you calculate the wavelength?

 

[benjammin54]

Make sure the amplitude is in meters, so 0.03 should be the amplitude