Ask Dr. Math

High School Archive

Browse High School Interest

Stars indicate particularly interesting answers or good places to begin browsing.

---

Accumulating Interest [06/26/2003]

Michael deposits $355 each month into an account that pays 3% interest, accrued monthly. How much money will he have after 3 months? 6 months? 12 months?

Calculating Interest on Auto Loans [7/10/1996]

How do the the lien holders for auto loans calculate interest on the principle?

Coal Consumption [01/13/1997]

How long will coal reserves last if consumption increase at the rate of 3.1 percent per year?

Formula for Compound Interest [3/31/1995]

Please send the formula(s) for calculating interest compounded annually, daily, and continuously.

Interest: Definitions [9/25/1996]

What is compound interest? What is continuous compounding?

Paying off the Mortgage [10/08/1998]

You have a 30-year mortgage with monthly payments of $370 at 8%. If you instead pay $400 each month, when will you pay it off?

Rate vs. Yield [01/31/2002]

What is the interest amount for the period from Sept. 05, 2001 to Dec. 04, 2001, at 5% interest, compounded daily, on principal of $356,964.15?

15 Percent Annual Interest [8/24/1996]

How much money will I will have in 29 years if I save $120 per month at 15 percent annual interest?

Amount of an RRSP [03/24/2002]

Brian makes $2500 deposits into his Registered Retirement Savings Plan on his 20th, 25th, 30th, 35th, and 40th birthdays. The RRSP pays 7% per annum, compounded annually. Determine the value of Brian's RRSP when he's 65.

Amount of Interest Earned in a Year [11/28/1995]

If Li Fong had earned one fourth of a percent more in annual interest on an investment, the interest for one year would have been $45 greater. How much did she invest at the beginning of the year?

Analyzing Monthly Payments [05/13/1998]

How much principal and how much interest have been paid after n payment cycles?

Annuities [12/31/2001]

If I have $100,000 at 5% interest and withdraw from it for 20 years, leaving a zero balance, how much monthly income will I have?

An Annuity [12/13/1995]

Compound interest with monthly installments.

Best Strategy for Paying Off Credit Card Debt [04/30/2007]

I have several credit cards, each with different balances and interest rates. I can pay a fixed amount each month to reduce my debt. How do I figure out the best way to distribute that payment to minimize my interest as much as possible?

Calculating Adjustable Rate Mortgages [04/25/2002]

If I am applying for a loan of $200,000 with the rate of 5.875 using a 3/1 ARM (adjustable rate mortgage), how do I calculate the payment?

Calculating an APR [10/01/2002]

A company made a loan for 12 months. The total amount was $790.60 and they charged $94.83 interest. How can I calculate the APR?

Calculating Monthly Payment on a Loan [03/22/2005]

What is the formula to calculate the monthly payment for a loan amortization table? Since the amount of principal and interest per payment both vary over the life of the loan, I'm not sure how to come up with that amount.

Car Loan Rates [08/27/1997]

Can you help me calculate the impact of different interest rates on a 5- yr. car loan (60 payments) of $20,000?

Compounding Interest and e [11/11/1998]

How is the number e derived from compounding interest? Does it come from the series expansion of e?

Compound Interest [04/11/1997]

How many years will be needed for $5000 to increase to $22,000 at 11 percent interest compounded monthly?

Compound Interest [07/30/1997]

I want to buy a car that costs $20,058.00 and would like to know how they calculate the interest on my loan.

Compound Interest [05/30/2001]

Computing compound interest with known variables.

Compound Interest - Rule of 70 [11/29/1994]

There is a famous "Rule of 70" for compound interest. What is it and why does it work?

Compound interest to a specific amount [07/24/1997]

How long would it take for a regular deposit account to equal one million dollars, assuming monthly payments of $100.00 at 8, 10 and 12 percent interest?

Compound interest with Repayments [07/24/1997]

I need a compound interest formula with repayments, such as in a bank situation.

Credit Card Calculations [1/24/1996]

I have textbooks and programs, none of which cover the calculation typical of credit card balance payoffs - how long will it take?

Credit Card Debt [05/09/1997]

How do credit card companies figure out how long it will take to pay off debt?

Declining Balance Interest [03/22/1999]

Can you explain declining balance interest to a high school business class?

Derivative of e^x [10/28/1999]

How can I prove that the derivative of e^x is e^x?

Dividing Investments for Maximum Return [09/26/1999]

How should one invest $60,000 in mutual funds with a return of 10% and municipal bonds with a return of 12% in order to maximize income?

Doubling Time [03/08/2002]

If the cost of an all-day ski lift ticket at Colorado's Vail Ski Area has been growing at about 7% per year ever since 1963, when a ticket was $5, what did it cost in 1993?

Endowment Awards [05/09/1997]

An endowment of $15,000 is made which earns 7.25% interest compounded continously. How large must the endowment grow for it to support an annual award of $1,200 in perpetuity?

Euler's Number [01/28/1998]

Why is Euler's number referred to as the natural base?

Exponential Growth & Compound Interest [6/2/1996]

(1) The cost of goods and services in an urban area increased 1.5% last month. If the rate continues, what will be the annual rate of increase? (2) Suppose a certain population increases by 30% every 10 years. By what percent does it increase each year?

Extra Loan Payments, Amortization Tables [03/31/1998]

If one extra payment is made each year, how much money will be saved over the life of a 30-year mortgage and how much sooner will it be paid off?

Financial Calculator: PerSense [03/19/2002]

What I understand is that part of the payment I make each month goes toward payment of the interest on the current balance of the loan, and part of it goes toward paying off the principal. Can you explain?

Finding Roots on a Calculator [04/22/2001]

How can I use the equation HPR = (1.667)^(1/5) on a calculator that does not have a fifth root key?

Formula for 8 Percent Interest [5/31/1996]

I put $15 a month into a saving account and at the end of each year I get 8 percent interest...

Formula for Mortgage [7/4/1996]

What is the formula for a mortgage?

Half Life of Money [04/13/2001]

What is the standard accepted formula for determining the amount of time it takes for money to lose half of its value due to inflation? I've found two, they are: t = t = log2/r and t = log2/log(1+r).

Page:  1  2 [next>]