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Question 870572: Jenny is given $5000 at age 5. Her parents place it in a bank account earning 7% interest compounded quarterly. Write an equation to model the amount of money in the account. Find how much money Jenny will have at age 18
Let x = number of interest periods y = 5000 * 1.07x
Let y = balance y = 5000 * 1.0713
Let a = initial deposit y = 5000 * 2.4098
Let b = interest rate y = 12049.23
y = a * bx Jenny has $12,049.23 at age 18.
y = 5000 * 1.07x
What was my Error?
I would like to know with these too.
3. The average number of minutes used on a cell phone each month in the year 2007 was 106 minutes. Since then, the number of minutes used each month has decreased by 2% each year. Write an equation to model the number of minutes used each month. Find the average number of minutes used on a cell phone in the year 2013.
Given Answer:
Let x = number of years since 2007 y = 106 * 1.02x
Let y = number of minutes used each month y = 106 * 1.026
Let a = number of minutes used each month in 2007 y = 106 * 1.12616
Let b = the decay factor y = 119.4
y = a * bx In 2013 the average number of
y = 106 * 1.02x minutes used each month was 119.
4. Todd deposited $7000 in a bank account earning 3% interest compounded yearly in 2008. Write an equation to model the amount of money in the account. Find how much money Todd will have in the account in 2015.
Given Answer:
Let x = number of interest periods y = 7000 * 1.03x
Let y = balance y = 7000 * 1.0315
Let a = initial deposit y = 7000 * 1.55796
Let b = interest rate y = 10905.77
y = a * bx Todd has $10,905.77 in 2015.
y = 7000 * 1.03x
Answer by MathTherapy(10552)   (Show Source):
You can put this solution on YOUR website!
I'll give you a hint for no. 1
You're seeking the FUTURE VALUE of $5,000, invested for 13 (18 - 5) years, and compounded quarterly at a rate of 7%
Future value formula:  , with:
P being principal or present value, or $5,000, in this case
A being accumulated amount, or the future value of P
r being the interest rate
m being the NUMBER of ANNUAL compounding periods (4 in this case, since it's compounded quarterly)
t being the time, in YEARS, that the money is invested
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