It is known as stimulus or the plural form stimuli. It can be external or internal.
A=P(1/2)^(t/h)
A=final amount
P=initial amount
t=time
h=half life
so
h=1.3 billlion (just write 1.3 and remember to mulipy the end time by 1 billion)
and final amount is 25% of original or 0.25P
0.25P=P(1/2)^(t/1.3)
divide both sides by P
0.25=(1/2)^(t/1.3)
take ln of bot sides
ln(0.25)=ln((1/2)^(t/1.3))
property of logarithms
ln(0.25)=(t/1.3)ln(1/2)
divide both sides by ln(1/2)
(ln(0.25))/(ln(1/2))=t/1.3
times both sides by 1.3
(1.3ln(0.25))/(ln(1/2))=t
remember that this is billion so
(1,300,000,000ln(0.25))/(ln(1/2))=t
2600000000.0001=t
about 2.6 billion years
DDT was one of the first chemicals in widespread use as a pesticide. Following World War II, it was promoted as a wonder-chemical, the simple solution to pest problems large and small. Today, nearly 40 years after DDT was banned in the U.S., we continue to live with its long-lasting effects:
<span>This is classified at being stage III. In stage III, the decubitus ulcer begins to show a breaking in the skin, throughout all layers. This is the most dangerous stage, and needs to be treated almost immediately. This will help to prevent any further damage that could be caused.</span>
