Answer
The amplitude of the two waves whose superposition gives this oscillation is $~~0.25~cm$
Work Step by Step
We can write a general expression for the standing wave:
$y'(x,t) = [(2y_m) sin ~(kx)]~cos~\omega t$
In the equation for the standing wave, we can see that $~~2y_m = 0.50~cm$
Then: $~~y_m = 0.25~cm$
The amplitude of the two waves whose superposition gives this oscillation is $~~0.25~cm$
