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: A and C
Step-by-step explanation:
So the largest rectangle has sides of 5 length and 2+4 width or 6 right. so 5*6=30 Now we have to find which of these expressions solve to get 30. I would just solve them all but the answer is
A and C
The answer would have to be D.
Answer:
86
Step-by-step explanation:
<u>Perimeter of WXY = WSY+WRX+XY</u>
<em>--> WSY = SY x 2</em>
--> WSY = 16 x 2 = 32
<em>Since it is an isosceles triangle, WRX = WSY</em>
--> WRX = 32
<em>--> Draw a straight line from W to XY to divide it into two halves assuming it to be point A. This would form a right angle triangle of WAX.</em>
<em>--> Solve it using the cos theta rule</em>
--> Angle = Angle X = 70°
Hypotenuse = WRX = 32
Adjacent = WA = ?
<em>--> Cos (Angle) = Adjacent/Hypotenuse</em>
Cos (70) = WA/32
WA = 10.9 rounded off to 11
--> WA=AY= 11
--> XY = WA + AY = 11+11 = 22
<em>--> Perimeter = WSY+WRX+XY</em>
Perimeter = 32+32+22
Perimeter = 86
Therefore, the perimeter of WXY is 86.