Interest Definition and 297 Threads

Interest, in finance and economics, is payment from a borrower or deposit-taking financial institution to a lender or depositor of an amount above repayment of the principal sum (that is, the amount borrowed), at a particular rate. It is distinct from a fee which the borrower may pay the lender or some third party. It is also distinct from dividend which is paid by a company to its shareholders (owners) from its profit or reserve, but not at a particular rate decided beforehand, rather on a pro rata basis as a share in the reward gained by risk taking entrepreneurs when the revenue earned exceeds the total costs.For example, a customer would usually pay interest to borrow from a bank, so they pay the bank an amount which is more than the amount they borrowed; or a customer may earn interest on their savings, and so they may withdraw more than they originally deposited. In the case of savings, the customer is the lender, and the bank plays the role of the borrower.
Interest differs from profit, in that interest is received by a lender, whereas profit is received by the owner of an asset, investment or enterprise. (Interest may be part or the whole of the profit on an investment, but the two concepts are distinct from each other from an accounting perspective.)
The rate of interest is equal to the interest amount paid or received over a particular period divided by the principal sum borrowed or lent (usually expressed as a percentage).
Compound interest means that interest is earned on prior interest in addition to the principal. Due to compounding, the total amount of debt grows exponentially, and its mathematical study led to the discovery of the number e. In practice, interest is most often calculated on a daily, monthly, or yearly basis, and its impact is influenced greatly by its compounding rate.

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  1. A

    Using Linear Interpolation to Find Interest

    Homework Statement Homework Equations The Attempt at a Solution I understand how they calculated NPW but how did they use the linear interpolation method?
  2. A

    Is there any way to derive an equation for compound interest based

    Is there any way to derive an equation for compound interest based on effective interest rate instead of the nominal interest rate?
  3. A

    What is the effective interest rate per period for compounding semiannually?

    Homework Statement I have borrowed $100. The interest rate is 5% per year compounded semiannually. How much will I have to pay the bank after 1 year? Homework Equations ##F=P(1+i)^{ n }##, where i is the effective interest rate per period and n represents the number of periods The Attempt...
  4. S

    Problem about relationships between interest factors

    Homework Statement The problem: Derive (3.3) without reference to (2.3) or (2.1). (2.1): F/P = (1 + i)^n (2.3): F/A = [(1 + i)^n – 1]/i (3.3): (F/A, i%, n) = (F/A, i%, n_1) + (F/P, i%, n_1) + (F/P, i%, n_1 + 1) + . . . + (F/P. i%, n – 1) (n > n_1) The solution (which also...
  5. B

    Advice for Parent of Child with Possible Science Interest

    Hi Everyone, I work for a large tech company full of Physicists, Electrical Engineers, etc. (full disclosure - I'm not an engineer). I think my son is demonstrating a potential future interest in Physics or Engineering based the types of things he plays with, the way he plays, and where...
  6. H

    Financial Calculations with Force of Interest

    Homework Statement You wish to invest $10,000 over 10 years. Available to you are 5 different funds. At any time you may transfer money from one fund to another without penalty or transaction fee. To optimize the money you receive at the end of 10 years you realize that you want all of your...
  7. B

    MHB Confirm Interest Rate Solution on Total Loan

    A small firm borrows \$1000 from a stockholder at a sim-pleinterest rate of 7.5%. The company secretary lends the firm an additional sum at a simple interest rate of 8.25%. At the end of one year, the firm repays a total of \$3997.75. How much did the secretary lend the firm and what is the...
  8. B

    MHB Find Difference in Total Cost for Engagement Ring at 2 Jewelers

    1. A prospective bridegroom wants to buy an engagement ring. Two jewelry stores each show him a ring at a cost of \$2400. One jeweler requires a 20% down payment with the balance to be paid at the end of one year at 11% simple interest. The other jeweler requires a 25% down payment with the...
  9. P

    Research interest, career plan, academic goal for REU

    Hello all, I'm a Mathematics and Physics major, currently in my junior year. Being an international student, it is extremely hard for me to find summer REU, so I could only find around 9 places. Even so, they only say that they MIGHT accommodate around 1-2 internationals. As such, I want to...
  10. I

    Greatest Balance After 8 Years: Compounded Interest Homework

    Homework Statement Assume that you can earn 6% on an investment, compounded daily. Which of the following options would yield the greatest balance after 8 years? -$20,000 now -$30,000 after 8 years -$8000 now and $20,000 after 4 years -$9000 now, $9000 after 4 years, and $9000...
  11. MarkFL

    MHB Al's question at Yahoo Answers regarding determining the accumulated interest

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  12. L

    Do you have any interest in Quaternionic Quantum Mechanics?

    Do you have any interest in Quaternionic Quantum Mechanics? As far as i know, there are some people have interest in research a new formulation of quantum mechanics using quaternionic, rather than complex, numbers.''Quaternionic Quantum Mechanics and Quantum Fields'',by Stephen L. Adler ,who...
  13. M

    Girlfriend talking to a previous love interest

    My girlfriend used to like some other guy and messed around with him once about a year ago, and I have been in a relationship with her for the past 3 months or so. She told me she hasn't talked to that guy in a long time, but today I looked on my computer and saw her e-mail open, so of course I...
  14. M

    What can I do to prepare for engineering classes and a career?

    Hello, Ive been considering a degree/ career in engineering but I have some concerns; 1st: I am 30 years old meaning if I start now I probably won't get started in my career till I'm about 34-35. and 2nd: its been a long time since high school and the closest thing I've had to a...
  15. R

    Programs Physics or Engineering undergraduate major: Interest Fluid Dynamics

    Currently I am intended to start next fall as a Physics major at the University of Delaware. My interest lies in Fluid Dynamics particularly in Geophysical Fluid Dynamics. I understand it's really early in my college career and I may change my interest, however I was surprised to find that as a...
  16. L

    Putting money in bank to get interest

    I have about 15k I want to put somewhere that will give me a good amount of interest. My current bank, Wells Fargo, gives me about 0.01% interest, which is so pathetic I'm actually losing more money than that from inflation. I've read that there are some banks that go up to 1%. They're like...
  17. M

    Nature of spacetime and interest in the field

    I am not quite sure what field the study of spacetime and energy would apply, considering I'm looking at it from a very, very big-picture point of view. I have a few theories and have done some math in regard to these three fields, and some of my conclusions have been quite interesting. I desire...
  18. 9

    Finance math: find total interest rate

    Homework Statement I am given this question: what is the monthly payment necessary to ammortize a loan of $100 000 at 2.3% compounded monthly for 20 years. I know the answer to the above: it is done by using the ammortization payment formula, in this case: R = 100 000...
  19. L

    MHB Converting to a tri-monthly interest rate

    If the APR is 3%, and I want to find the tri-monthly interest rate, is the correct way to find it: (0.03+1)^(4/12)-1 ?
  20. T

    Job Skills I'm interest in resume feedback

    Hey everyone, I'm an Electrical Engineering major in my third year now at Cal Poly Pomona after transferring from a city college. I am applying for undergraduate research internships this summer and would really appreciate feedback on my resume, especially from those in research. I'd...
  21. Y

    Auto Insurance monthly interest rate. Having trouble

    [b]1. If you took out a $11,250 car loan at 3.840 % for 5 yrs (60 months), (a) what would be the monthly payment? (b) what is the difference between paying the $11,250 up front versus taking a loan out for it? [b]2. Interest formula: I= P r T [b]3. (a) I= (11,250)(.03840)(5)...
  22. H

    Logarithm: Compound interest problem

    Homework Statement How long does it take for a sum of money to double if it is invested at 8% compounded semi-annually? Homework Equations A = P(1+i)n A: Compounded amount P: Initial amount i: Interest rate n: Period The Attempt at a Solution A = P(1+i)n (2x) = (x)[1+(0.08)]2n (2n because...
  23. I

    Career options for double engineering interest?

    Well I'm interested in both mechanical engineering and engineering physics. Are there any further academic fields or career options that combine such interests/fields? thanks.
  24. xortan

    Difference equation for interest and bank account

    Homework Statement Consider your bank offers a 2% annual interest rate, and has no annual service charge. Let y[n] represent your account balance at the beginning of the month n and x[n] represent the amount of money you deposit during the month n. Assume that deposits during month n are...
  25. F

    Medical Radiation and Health Interest Group

    Dear Colleagues, Is there anyone here who would be interest in sharing articles, data, theories, and discussions on risks of EMF, RF, radiation emission from devices and man made structures and health consequences and epidemiology. Please contact or send a follow up post here. I am...
  26. A

    Differential equations interest probelm

    Homework Statement Two same aged people P1,P2 create bank accounts at ages 25,35 respectively, and add 2000 euros annualy , for 10,30 years respectively. No initial capital in the accounts. 1.For interest 8% , what's the balance of each acount at age of 65 of P1,P2? 2.What should be the...
  27. L

    My interest leans towards Electrical/Computer/Electronics engineering?

    Currently I'm in a dilemma whether which of the 2 engineering actually suits what I want to pursue/do in the future... Background: After completing my high school, I can conclude that I have deep interest in physics, chemistry, programming, calculus which I didn't have much of a problem...
  28. Jameson

    MHB Debbie's question from Facebook on interest rates

    I'm needing help w/ an accounting issue that deals with applying interest annually. The interest rate is 10%. It doesn't say if it's compounded or simple so which is to be used? If you start with a balance of \$20323.64 in Jan, and make twelve monthly payments of \$200 each (total \$2400) how...
  29. H

    How Do You Model Compound Interest with Differential Equations?

    Homework Statement Assume that Po dollars is deposited into an account paying r percent compounded continuously. If withdrawals are at an annual rate of 200t dollars (assume these are continuous) find the amount in the account after T years. The Attempt at a Solution I have two differential...
  30. L

    Compounding interest formula going awry

    If Po dollars are deposited in an account paying r percent compounded continuously and withdrawals are at a rate of 200t (continuously), what is the amount after T years? I derived the formula by taking the limit as m -> ∞ of the compounding interest equation P(t) = Po(1+r/m)^mt which gives...
  31. L

    Schools Graduate school personal statement- how specific about field of interest?

    I'm working on writing my graduate school application right now. It was easy to talk about my academic qualifications and all the research I have done. But I don't know how specific I need to get when talking about what I'm interested in. I'm a chemistry major. I have a broad interest in...
  32. S

    Everytime I start doing math on paper I lose interest

    I then think that I *should*be spending my time in something more "practical" like R or C++ or matlab...then stop the math to code lol When I do a lot of coding I notice I go to the math and find that I'm able understand it easier because the notation/syntax is so much less busy. Do the...
  33. H

    Interest in Linear algebra and Differential Equations?

    I'm a college student whose been force enrolled in Linear Algebra and Differential Equations. No offence to math lovers but I don't find them very interesting. I study much better in courses which I find interesting so could someone please point out interesting applications of L.A. and D.E...
  34. H

    MHB Balance After 5 Years of Compound Interest on Monthly Deposits

    So I'm trying to find out the formula by writing out the expanded version first and simplifying it, but I'm not sure how to write this in terms of exponents. Month 1: 25 + 25(.05) Let x = 25 + 25(.05) Month 2: (x + 50)(.05) + (x + 50) Month 3: ((x + 50)(.05) + (x + 50) + 75)(.05) + ((x +...
  35. T

    Geometric sequence, find the best interest option over a year

    Homework Statement The Bank of Utopia offers an interest rate of 100% per annum with various options as to how the interest may be added. A man invests $1000 and considers the following options. Option A - Interest added annually at the end of the year. Option B - Interest of 50% credited...
  36. P

    Interest in being a physicist what to take?

    Interest in being a physicist.. what to take?? Hey I'm in a dilemma right now so I really need help. I want to study physics in the future and be able to write my own research papers. But I also want to get a settled job first to keep my options open in the future. I won't take engineering...
  37. ShawnD

    Derivative of the compound interest equation

    I'm trying to prove a point to someone about compounding periods and mortgage payments. Interest is calculated as $ = P(1 + I/x)^x where P is how much you borrowed, I is "annualized" interest rate and x is how many compound periods are in a year. For example, a credit card at 20% compounded...
  38. I

    Principal( 1 + interest )exponent [on a simple calc.]

    can you tell me how to do compound interest calculations with a calculator that has only plus, minus, divide, multiply?final = Principal( 1 + interest )exponent
  39. G

    Financial Maths: Simple/Compound Interest

    Homework Statement As a financial advisor, you have been requested to analyse the following alternative sources of finance for your client who currently has a funding need of $1,000,000 for 5 years. The three borrowing options that have been presented to you are: Option 1: ABC Friendly...
  40. Y

    Schools Declaring / Indicating Area of Interest Grad School

    Before I begin, I am still a year removed from applying to grad schools. However, it never hurts to read up on some information beforehand. How binding and obligatory is the initial declaration of area of interest on the application? In other words, once you get into grad school, can you...
  41. B

    Are Real and Nominal Interest Rates Identical in Monetary Policy Analysis?

    In the Money Supply-Money Demand curve, the equilibrium interest rate is the real or nominal interest rate? Or are they the same thing for the purposes of evaluating monetary policy? BiP
  42. J

    Will My PhD Topic Restrict My Career Options and Are Australian Universities Well-Regarded Globally?

    I have been offered a PhD at a TOP institution. The problem is, it is in rather an applied field. I am also waiting upon an offer from ANU (Australian National University) in a fundamental topic. Both are world recognised universities, though the former is of the top few. My worry is that I will...
  43. W

    MHB What is the formula for calculating future value with increasing interest rates?

    YR RATE INTEREST BALANCE 0 1000.00 1 .03 30.00 1030.00 2 .033 33.99 1063.99 3 .0363 38.62 1102.61 4 .03993 44.03 1146.64 Above is an example of future value of an amount at an incresing...
  44. D

    Figuring out compounding interest

    I talk to people a lot about the power in investing their money. I've always relied on Excel to figure out things though and I'm getting sick of it. So I figured there was a way to do it simpler with math than making gigantic lists that detailed every month and year a person invests money...
  45. T

    Why is the Forward Rate Greater Than the Zero Rate and Yield?

    I came across this question in chapter 4 of Hull 'Options Futures and other Derivatives'. I have the answer but I am not sure what the explanation is. Could anyone help? The term structure of interest rates is upward sloping. Put the following in order of magnitude : a) the 5 year zero...
  46. G

    Compound Interest Formula and Natural Logarithms

    Homework Statement Solve the compound interest formula for r by using natural logarithms. Homework Equations A=P(1+r/n)nt The Attempt at a Solution 1400 = 1000(1+r/360)(360*2) 1.4 = (1+r/360)720 ln(1.4) = 720ln((360+r)/360) I'm not sure where to go after this. Did I...
  47. D

    Statement of interest for math REU

    I have to write a statement of interest for a math reu application. I was going to just write a formal essay. Then I thought, maybe I can write this essay in the form of a proof with lemmas and a theorem which will say that I will be a good fit for your program. Do you think this is stupid? It's...
  48. T

    Podcast about Material Science that maybe of interest.

    Thought this podcast may be of interest to you guys. It's from Boise State's (where I went to school and work with now) Beyond the Blue program, which is a podcast series that spotlights various academics from the university. This one is from Amy Moll, who is a professor of material science...
  49. U

    Where to start learning more about and start building interest in EE?

    I've always found electrical engineering interesting and I am considering pursuing in a career in this in the future. I'm a junior in high school and I want to be positive that this is what I want to study for in college. So I want to start learning more about this and playing around with this...
  50. N

    Interest in physics, but no real foundation in mathematics past pre-calc.

    Try and make this short... starting with the fact that I never attended in any way shape or form 6th-8th grade. Bullying, family (or lack thereof) issues, was depressed and ended up being "home schooled". Except after like two weeks my dad gave up and I just stopped studying anything school...
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