Answer:
i think is Destruction of coral 
 
        
                    
             
        
        
        
Half life formula
The number of unstable nuclei remaining after time t can be determined according to this equation:
N(t) = N(0) * 0.5^(t/T)
where:
N(t) is the remaining quantity of a substance after time t has elapsed.
N(0) is the initial quantity of this substance.
T is the half-life.
It is also possible to determine the remaining quantity of a substance using a few other parameters:
N(t) = N(0) * e^(-t/τ)
N(t) = N(0) * e^(-λt)
τ is the mean lifetime - the average amount of time a nucleus remains intact.
λ is the decay constant (rate of decay).
All three of the parameters characterizing a substance's radioactivity are related in the following way:
T = ln(2)/λ = ln(2)*τ
How to calculate the half life
Determine the initial amount of a substance. For example, N(0) = 2.5 kg.
Determine the final amount of a substance - for instance, N(t) = 2.1 kg.
Measure how long it took for that amount of material to decay. In our experiment, we observed that it took 5 minutes.
Input these values into our half life calculator. It will compute a result for you instantaneously - in this case, the half life is equal to 19.88 minutes.
If you are not certain that our calculator returned the correct result, you can always check it using the half life formula.
 
        
             
        
        
        
Answer:
Given merely 40 butterflies were marked, assumed that there were multiple captures of both marked and unmarked butterflies, that the butterflies caught in traps were on the loose to be caught again. There are two mathematical solutions for this, both yielding the same answer which is 100. 
•	First, to each marked butterfly was taken twice (40 marked X2 = 80 captured) then of the unmarked butterflies the 120 captured must relate to 60 actual butterflies. In which 40 + 60 = 100. 
•	Secondly, by means of ratios in which 80/200 = 40/X. In this case X also = 100 that will result to the estimated size of the population of wilson park is 100.
Explanation:
 
        
             
        
        
        
SOS:
The answer is <em><u>gametes!</u></em>
<em>Hope this helps!</em>