Question

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.

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Answer 1

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)*

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.

f(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)”, 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 2

Answer:

Required Answer:

We are given with a table which shows the number of months working at part-time job by Juanita and her monthly savings.

Given Table:

0 month - $36

2 month - $60

4 month - $84

6 month - $108

8 month - $132

At first, Juanita have saved 36 dollars before the starting of her part time job. After 2 months, her monthly saving is increased from 36 dollars to 60 dollars

\sf{ \longrightarrow{2 \: months = 60 - 36 }}⟶2months=60−36

\sf{ \longrightarrow{2 \: months = 24}}⟶2months=24

Now money saved by her in 1 month,

\sf{ \longrightarrow{1 \: month = 12}}⟶1month=12

As we can see that this savings are increasing at a regular rate with certain time interval of 2 months. After the above calculation we got that she is saving $12 per month.

The correct answer is:

Option A