Find the third harmonic (Sound Physics)

[Divinite]

Question: The frequencies of the first three harmonics of a 300 Hz square wave are 300 Hz, 900 Hz, and 1500 Hz. If the amplitude of the fundamental is 1.00 A, then the amplitudes of the second harmonic is _____ A, and the amplitude of the third harmonic is _____ A.

I found the answer to the second harmonic, by using the formula: A_n = 2/(pi*n). I did 2/(pi*2) and got 0.3183.

For the third harmonic I tried doing 2/(pi*3), which got me 0.2122, but that does not seem to be the answer.

 

[Divinite]

Update: The answer was correct, just not rounded properly.
Thanks.