Set this up as
10 = 40 (1/2)t/28
and solve for t in years.
10/40 = (1/2)t/28
log(0.25) = (t/28) log(0.5)
t = 28 log(0.25) / log(0.5) years = 56 years
Test the answer:
56 years = 2(28 years) = 2 half-lives, so the remaining amount should be 1/2 of 1/2 of the initial amount, i.e. 1/4 of the initial amount, and 10 mg = 1/4 of 40 mg.
<span>There Are Four Main Arthropod Families.
Arthropods Account for 80 Percent of All Animal Species
Arthropods Are a Monophyletic Animal Group
The Exoskeleton of Arthropods Is Composed of Chitin</span>
They form when wind blows over the surface of the ocean. Wind energy is transferred to the sea surface. Then, the energy is carried through the water by the waves. This gives waves the energy to erode the shore.
