> (7)
Plugging the experimentally measured values for m and d1, and the value k calculated using equation 2, this gives a "levitating time" for the metal Slinky of t = 0.29 ± 0.05 seconds. This corresponds relatively well to the experimental value of t = 0.4 ± 0.1 seconds.
This is an undergrad homework assignment but I would not call this a relatively well approximation of the experimental value.