a) Speed = 90cm/1.69seconds ≈ 53.3cm/s (3s.f.)
b) No it is not possible. Adjusting either the amplitude or the damping does not affect the speed of the wave pulse. But, adjusting the tension would change the speed and the wavelength.
(The below pictures are some factors that we changed, but only changing the tension will change the speed.)
Done By: Benjamin Fheng and Lee Si Yuan :D