question 4.4 
The position of a mass that vibrates at the end of a spring with negligible mass is given by u = 3.cm e-6.38 t sin (15.6 t + 1.12), where t is measured in seconds and the full argument of the sine is expressed in radians. What is the logarithmic decrement? This is the natural logarithm of the ratio of the amplitude at any given time to the amplitude a period of the muted vibration later. 
Select the correct answer from the following list: 
a).828e-1 
b) 129e-2 
c) .411 
d)2.58