78....................................................
A = 1/2bh
40 = 1/2 x^2
x^2 = 80
x = 8.9
Answer:
Step-by-step explanation:
multiply lengthx weith
The amount of the radioactive material in the vault after 140 years is 210 pounds
<h3>How to determine the amount</h3>
We have that the function is given as a model;
f(x) = 300(0.5)x/100
Where
- x = number of years of the vault = 140 years
- f(x) is the amount in pounds
Let's substitute the value of 'x' in the model
f(x) = 300(0.5)x/100


f(140) = 210 pounds
This mean that the function of 149 years would give an amount of 210 pounds rounded up to the nearest whole number.
Thus, the amount of the radioactive material in the vault after 140 years is 210 pounds
Learn more amount radioactive decay here:
brainly.com/question/11117468
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Answer:
![c(t) = 120 [0.7]^{t}](https://tex.z-dn.net/?f=c%28t%29%20%3D%20120%20%5B0.7%5D%5E%7Bt%7D%20)
Step-by-step explanation:
At the moment a certain medicine is injected, its concentration in the bloodstream is 120 milligrams per liter.
From that moment forward, the medicine's concentration drops by 30% each hour.
Therefore, the medicine concentration c(t) in mg/liters after t hours will be modeled as
![c(t) = c(0) [1 - \frac{30}{100}]^{t}](https://tex.z-dn.net/?f=c%28t%29%20%3D%20c%280%29%20%5B1%20-%20%5Cfrac%7B30%7D%7B100%7D%5D%5E%7Bt%7D%20)
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