Given that the rate of Uranium decay is 57%, this means that after each day, only 0.43 of the mass from the prior day is left. The equation that would best represent the scenario is,
a(t) = a₁(0.43^t)
where a(t) is the mass after t days and t is the number of days. Substituting,
a(t) = 3,280(0.43^15)
= 0.01 lbs.
