The amount of money in an account may increase due to rising stock prices and decrease due to falling stock prices. Mason is studying the change in the amount of money in two accounts, A and B, over time.
The amount f(x), in dollars, in account A after x years is represented by the function below:
f(x) = 10,125(1.83)x
Part A: Is the amount of money in account A increasing or decreasing and by what percentage per year? Justify your answer. (5 points)
Part B: The table below shows the amount g(r), in dollars, of money in account B after r years.
r (number of years) 1 2 3 4
g(r) (amount in dollars) 9,638 18,794.10 36,648.50 71,464.58
Which account recorded a greater percentage change in amount of money over the previous year? Justify your answer.
Answers
Account A: Decreasing at 8 % per year
Account B: Decreasing at 10.00 % per year
Account B shows the greater percentage change
Step-by-step explanation:
Part A: Percent change from exponential formula
f(x) = 9628(0.92)ˣ
The general formula for an exponential function is
y = ab^x, where
b = the base of the exponential function.
if b < 1, we have an exponential decay function.
ƒ(x) decreases as x increases.
Account A is decreasing each year.
We can rewrite the formula for an exponential decay function as:
y = a(1 – b)ˣ, where
1 – b = the decay factor
b = the percent change in decimal form
If we compare the two formulas, we find
0.92 = 1 - b
b = 1 - 0.92 = 0.08 = 8 %
The account is decreasing at an annual rate of 8 %.The account is decreasing at an annual rate of 10.00 %.
Account B recorded a greater percentage change in the amount of money over the previous year.
Answer:
The u-v method to find focal length of a given concave mirror or convex lens consists of following steps. For an appropriate object distance u, find the image distance v. Measure u and v. Repeat above step at few more object distances.