Answer:
<u>42.25π m²</u>
Step-by-step explanation:
Let's solve!
⇒ Take the radius of the lawn to be 'r'
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Then, area of the path equals :
⇒ Area of (lawn + path) - Area of lawn
⇒ π (r + 2)² - πr² = 30π
⇒ πr² - πr² + 4πr + 4π = 30π
⇒ 4πr = 26π
⇒ r = 6.5 m
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Area of the lawn :
⇒ Area = πr²
⇒ Area = π × (6.5)²
⇒ Area = <u>42.25π m²</u>
It would take the pottery maker 2 hours to make a vase.
Answer:
If you have a quantity X of a substance, with a decay constant r, then the equation that tells you the amount of substance that you have, at a time t, is:
C(t) = X*e^(-r*t)
Now, we know that:
We have 2000g of substance A, and it has a decay constant of 0.03 (i assume that is in 1/year because the question asks in years)
And we have 3000 grams of substance B, with a decay constant of 0.05.
Then the equations for both of them will be:
Ca = 2000g*e^(-0.03*t)
Cb = 3000g*e^(-0.05*t)
Where t is in years.
We want to find the value of t such that Ca = Cb.
So we need to solve:
2000g*e^(-0.03*t) = 3000g*e^(-0.05*t)
e^(-0.03*t) = (3/2)e^(-0.05*t)
e^(-0.03*t)/e^(-0.05*t) = 3/2
e^(t*(0.05 - 0.03)) = 3/2
e^(t*0.02) = 3/2
Now we can apply Ln(x) to both sides, and get:
Ln(e^(t*0.02)) = Ln(3/2)
t*0.02 = Ln(3/2)
t = Ln(3/2)/0.02 = 20.3
Then after 20.3 years, both substances will have the same mass.
Answer:
73,084
Step-by-step explanation:
