Answer:
12
Explanation:
Suppose the four different strains are P, Q, R, S. Thus, the first infection can be from any of the four strains and it occurs in 4 ways.
Since an individual cannot be infected again with the strain from which he/she is been previously infected;
Then, at the second time;
The possible number of strain to be infected with = 4-1 = 3 ways
Thus; the number of possible different levels of severity can be viewed by forming two lettered word P, Q, R, and S without repetition which is:
= 4 × 3
= 12
It depends on where the fuel source is coming from and also how much fuel is there.
~Hello there! ^_^
Your question: How often is CO2 cycled through the atmosphere?
Your answer: CO2 is cycled through the atmosphere in 350 years.
Hope this helps~
This movement is called diffusion
There are about 250 chemicals that are harmful including carbon monoxide and ammonia.
