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.
Answer:
Until early 1970's the Turkish Straits were known as a rich and productive marine area. The Straits also used to play an important role as a biological corridor between the Mediterranean and the Black Sea, and acted as an acclimatization zone for the Mediterranean species.
The Tigris and Euphrates rivers provided Mesopotamia with enough fresh water and fertile soil to allow ancient people to develop irrigation and grow supplies surplus.
The role the Tigris and Euphrates river played in the development of civilization is that they enriched the soil and helped farmers grow supplies surpluses.
Explanation:
Answer:
They are weather systems that happen to spin in a counterclockwise direction in the Northern Hemisphere from low pressure points. They form between two big cold fronts when their temperatures are very different compared to each other. These air masses will blow past each other in opposite directions when it is formed.
Answer:
Columbus set sail from Spain to find an all-water route to Asia.
Explanation:
