ρ= 0.0037/0.9= 0.00411kg/m
v=√(T/ρ) = √(530/0.00411)= 359.053m/s
n=1: f=nv/2L = 1*359.053/(2*0.62)= 289.5588= 289.6[Hz] fundamental frequency.
n=2: f= 2*359.053/(2*0.62)= 579.117= 579.1[Hz] 1st.overtone.
n=3: f= 3*359.053/(2*0.62)= 868.676= 868.7[Hz] 2nd.overtone.