We want to see how long will take a healthy adult to reduce the caffeine in his body to a 60%. We will find that the answer is 3.55 hours.
We know that the half-life of caffeine is 4.8 hours, this means that for a given initial quantity of coffee A, after 4.8 hours that quantity reduces to A/2.
So we can define the proportion of coffee that Jeremiah has in his body as:
P(t) = 1*e^{k*t}
Such that:
P(4.8 h) = 0.5 = 1*e^{k*4.8}
Then, if we apply the natural logarithm we get:
Ln(0.5) = Ln(e^{k*4.8})
Ln(0.5) = k*4.8
Ln(0.5)/4.8 = k = -0.144
Then the equation is:
P(t) = 1*e^{-0.144*t}
Now we want to find the time such that the caffeine in his body is the 60% of what he drank that morning, then we must solve:
P(t) = 0.6 = 1*e^{-0.144*t}
Again, we use the natural logarithm:
Ln(0.6) = Ln(e^{-0.144*t})
Ln(0.6) = -0.144*t
Ln(0.6)/-0.144 = t = 3.55
So after 3.55 hours only the 60% of the coffee that he drank that morning will still be in his body.
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brainly.com/question/19599469
Answer:
B
Step-by-step explanation:
Answer:
x = 35
Step-by-step explanation:
Solve for x:
6 x - 15 = 4 x + 55
Hint: | Move terms with x to the left hand side.
Subtract 4 x from both sides:
(6 x - 4 x) - 15 = (4 x - 4 x) + 55
Hint: | Combine like terms in 6 x - 4 x.
6 x - 4 x = 2 x:
2 x - 15 = (4 x - 4 x) + 55
Hint: | Look for the difference of two identical terms.
4 x - 4 x = 0:
2 x - 15 = 55
Hint: | Isolate terms with x to the left hand side.
Add 15 to both sides:
2 x + (15 - 15) = 15 + 55
Hint: | Look for the difference of two identical terms.
15 - 15 = 0:
2 x = 55 + 15
Hint: | Evaluate 55 + 15.
55 + 15 = 70:
2 x = 70
Hint: | Divide both sides by a constant to simplify the equation.
Divide both sides of 2 x = 70 by 2:
(2 x)/2 = 70/2
Hint: | Any nonzero number divided by itself is one.
2/2 = 1:
x = 70/2
Hint: | Reduce 70/2 to lowest terms. Start by finding the GCD of 70 and 2.
The gcd of 70 and 2 is 2, so 70/2 = (2×35)/(2×1) = 2/2×35 = 35:
Answer: x = 35
