If there initially 12 grams of the substance, 5.35 grams will remain after 3 hours
The initial amount, a = 12 grams
The amount after 2 hours, y = 7 grams
Time taken, x = 2 hours
First, let us calculate the decay constant, b
The formula for the final value of an exponential decay is:
[tex]y=a(1-b)^x[/tex]
Substitute y = 12, a = 7, and x = 2 into the equation to solve for b
[tex]7=12(1-b)^2\\\\\frac{7}{12} = (1-b)^2\\\\0.583=(1-b)^2\\\\\sqrt{0.583} = 1 - b\\\\0.764=1-b\\\\b=1-0.764\\\\b=0.236[/tex]
The decay constant, b = 0.236
After 3 hours:
Substitute x = 3, a = 12, and b = 0.236 to solve for y
[tex]y=a(1-b)^x\\\\y=12(1-0.236)^3\\\\y = 5.35[/tex]
Therefore, 5.35 grams will remain after 3 hours
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