MHB Annual Average Percentage Increase

  • Thread starter Thread starter linapril
  • Start date Start date
  • Tags Tags
    Average increase
AI Thread Summary
To find the annual average percentage increase of a house that doubles in value over 20 years, the formula used is H = H0(1+r)^t. By setting H = 2H0 and t = 20, the equation simplifies to 2 = (1+r)^20. Solving for r involves raising both sides to the power of 1/20 and subtracting 1, leading to an approximate annual increase of 3.53%. The discussion emphasizes the simplicity of this calculation and suggests clearer topic titles for future queries.
linapril
Messages
22
Reaction score
0
What is the simplest way of solving this?

The value of a house is doubled in 20 years. What is the annual average percentage increase, if it is assumed to be the same each year?
 
Mathematics news on Phys.org
I would let $H_0$ be the initial value of the house, and use the relation:

$\displaystyle H=H_0(1+r)^t$

We then let $H=2H_0$, $t=20$ and solve for $r$:

$\displaystyle 2H_0=H_0(1+r)^{20}$

$\displaystyle 2=(1+r)^{20}$

Now, raise each side to a power of $\dfrac{1}{20}$, then subtract 1 from each side, and you will have isolated $r$. Then multiply by 100, and use your calculator to get a decimal approximation if you want.

edit: Please let me suggest that your topic titles be more indicative of the nature of the question. I would use something like "Computing growth rate of investment" or something similar.
 
linapril said:
What is the simplest way of solving this?

The value of a house is doubled in 20 years. What is the annual average percentage increase, if it is assumed to be the same each year?
Very easy indeed...

$a= 2^{\frac{1}{20}} \sim 3.53 \text{%}$

Kind regards

$\chi$ $\sigma$
 
Could please explain how you got that answer?

chisigma said:
Very easy indeed...

$a= 2^{\frac{1}{20}} \sim 3.53 \text{%}$

Kind regards

$\chi$ $\sigma$
 
linapril said:
Could please explain how you got that answer?

MarkFl has already explained that in excellent way!... an alternative explanation is that the expression of the of value of the house after N years is...

$\displaystyle v= 2^{\frac{N}{20}}$ (1)

Now all what You have to do is setting in (1) N=1...

Kind regards

$\chi$ $\sigma$
 
Seemingly by some mathematical coincidence, a hexagon of sides 2,2,7,7, 11, and 11 can be inscribed in a circle of radius 7. The other day I saw a math problem on line, which they said came from a Polish Olympiad, where you compute the length x of the 3rd side which is the same as the radius, so that the sides of length 2,x, and 11 are inscribed on the arc of a semi-circle. The law of cosines applied twice gives the answer for x of exactly 7, but the arithmetic is so complex that the...
Back
Top