A 10.6 kg object oscillates at the end of a vertical spring that has a spring constant of 2.05 * 10^4 N/m. The effect of air resistance is represented by the damping coefficient b= 3.00 Ns/m. (a) Calculate the frequency of the damped oscillation. (b) By what percentage does the amplitude of the oscillation decrease in each cycle? (c) Find the time interval that ellapses while the energy of the system drops to 5.00% of it's initial value.

I know the frequency is 7 Hz. For part b, I'm getting 1% and the answer is supposed to be 2%. Can you help me?