Using an exponential function, it is found that:
a) [tex]N(t) = 75(0.5)^{\frac{t}{3.8}}[/tex]
b) 37.5 grams of the gas remains after 3.8 days.
c) The amount remaining will be of 10 grams after approximately 11 days.
What is an exponential function?
A decaying exponential function is modeled by:
[tex]A(t) = A(0)(1 - r)^t[/tex]
In which:
- A(0) is the initial value.
- r is the decay rate, as a decimal.
Item a:
We start with 75 grams, and then work with a half-life of 3.8 days, hence the amount after t daus is given by:
[tex]N(t) = 75(0.5)^{\frac{t}{3.8}}[/tex]
Item b:
This is N when t = 3.8, hence:
[tex]N(t) = 75(0.5)^{\frac{3.8}{3.8}} = 37.5[/tex]
37.5 grams of the gas remains after 3.8 days.
Item c:
This is t for which N(t) = 10, hence:
[tex]N(t) = 75(0.5)^{\frac{t}{3.8}}[/tex]
[tex]10 = 75(0.5)^{\frac{t}{3.8}}[/tex]
[tex](0.5)^{\frac{t}{3.8}} = \frac{10}{75}[/tex]
[tex]\log{(0.5)^{\frac{t}{3.8}}} = \log{\frac{10}{75}}[/tex]
[tex]\frac{t}{3.8}\log{0.5} = \log{\frac{10}{75}}[/tex]
[tex]t = 3.8\frac{\log{\frac{10}{75}}}{\log{0.5}}[/tex]
[tex]t \approx 11[/tex]
The amount remaining will be of 10 grams after approximately 11 days.
More can be learned about exponential functions at https://brainly.com/question/25537936
