b
Step-by-step explanation:
x
The linear equation for the remaining Federal Helium Reserves, r(t) = 20 -1.9t
There is 20 billion cubic feet of Helium in 2010. Helium is depleted by about 1.9 billion cubic feet each year.
Let 'r' denotes the remaining Federal Helium Reserves in billions of cubic feet.
Let 't' denotes the number of years since 2010.
We have to find a linear equation to represent the depletion of Helium through years since 2010. A linear equation will have two variables, one dependent and one independent variable. Here, let 'r' be the dependent variable and 't' be the independent variable.
Then the amount of Helium depleted in 't' years = 1.9t
So, the remaining Helium in the Federal Helium Reserve since 2010 = 20 - 1.9t.
Thus, r(t) = 20 - 1.9t
This is a linear equation because it depends on only one variable, 't'.
Learn more about linear equations at brainly.com/question/15602982
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Answer:

Step-by-step explanation:
Given the geometric sequence
-0.6, 3, -15, 75, ...
Common ratio, 
The next term,
is obtained by multiplying the previous term c(n-1) by -5.
Therefore, the recursive formula for the sequence is:

The standard deviation shows the dispersion (how close) of the data. Therefore the correct statement is A:
<span>A- Raquel’s data are most likely closer to $3.42 than Van’s data are to $3.78.</span>