I was doing my summaries today and i think you have to you use Wien's Law for that one even though it's not actually stated. Because from the graph you can determine the wavelength at which the intensity (i.e. energy output) peaks and this is your max wavelength. Then using Wein's Law you have
max wavelength = W/T where W is a constant 2.89 times 10^-3
T is temp so you can figure it out..
