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:
r=2
Step-by-step explanation:
y = k x^r is the formula for a direct variation
y = k x^ -r is the formula for a indirect variation
20= 5 (1/2)^ -r
Divide each side by 5
4 = (1/2) ^ -r
Rewriting
2^2 = 2^ -1 ^ -r
2^2 = 2 ^ r
The bases are the same so
2 =r
Answer:
<DCA and <BCF
Step-by-step explanation:
The vertically opposite angles are the angles <DCA and <BCF. These angles are always equal.
- When two lines cross, two angles that are vertical two one another are equal.
- They are know as vertically opposite angles.
- When two straight lines cross each other, four angles are produced.
- The two vertically opposite have the same values.
Answer:
economy class = 260
business class = 100.
Step-by-step explanation:
for every 13 economy seats, there are 5 business class seats
EC = 13
BC = 5
ADD to get total = 18
divide 360 by 18 to get the number of groups created.
you get 20.
multiply 20 by each class seats
13 by 20 = 260
5 by 20 = 100
you can confirm by adding the seats to see if you will get 360.
