## Chapter 4 Class Handout

**Simple Interest: A = P(1+rt)**

**P:**the major, the amount invested

**A:**the new balance

**t:**the time

**r:**the rate, (in decimal form)

**Ex1:**If $1000 is invested currently through basic interemainder of 8% per year. Find the new amount after two years.P = $1000, t = 2 years, r = 0.08. A = 1000(1+0.08(2)) = 1000(1.16) = 1160

## Compound Interest:

**P:**the principal, amount invested

**A:**the new balance

**t:**the time

**r:**the price, (in decimal form)

**n:**the number of times it is compounded.

You are watching: Suppose you deposit 5000 in a savings account

**Ex2:**Suppose that $5000 is deposited in a saving account at the price of 6% per year. Find the complete amount on deposit at the finish of 4 years if the interemainder is:P =$5000, r = 6% , t = 4 yearsa)

**simple**: A = P(1+rt) A = 5000(1+(0.06)(4)) = 5000(1.24) = $6200b) compounded

**annually**, n = 1:

**A = 5000(1 + 0.06/1)(1)(4) = 5000(1.06)(4) = $6312.38c) compounded semiannually**, n =2: A = 5000(1 + 0.06/2)(2)(4) = 5000(1.03)(8) = $6333.85d) compounded

**quarterly**, n = 4: A = 5000(1 + 0.06/4)(4)(4) = 5000(1.015)(16) = $6344.93e) compounded

**monthly**, n =12: A = 5000(1 + 0.06/12)(12)(4) = 5000(1.005)(48) = $6352.44f) compounded

**daily**, n =365: A = 5000(1 + 0.06/365)(365)(4) = 5000(1.00016)(1460) = $6356.12

## Continuous Compound Interest:

Continuous compounding implies compound eextremely instant, think about investment of 1$ for 1 year at 100% interest price. If the interest price is compounded n times per year, the compounded amount as we saw prior to is provided by:**A = P(1+ r/n)nt**

**the following table mirrors the compound interemainder that outcomes as the number of compounding durations increases:P = $1; r = 100% = 1; t = 1 yearCompoundedNumber of periods per yearCompound amountannually1(1+1/1)1 = $2monthly12(1+1/12)12 = $2.6130daily360(1+1/360)360 = $2.7145hourly8640(1+1/8640)8640 = $2.71812each minute518,400(1+1/518,400)518,400= $2.71827As the table mirrors, as n rises in size, the limiting value of A is the distinct number e = 2.71828**If the interemainder is compounded repeatedly for t years at a price of r per year, then the compounded amount is given by:

**A = P. e rt**

**Ex3:**Suppose that $5000 is deposited in a saving account at the price of 6% per year. Find the total amount on deposit at the end of 4 years if the interest is compounded continuously. (compare the outcome through example 2)P =$5000, r = 6% , t = 4 yearsA = 5000.e(0.06)(4) = 5000.(1.27125) = $6356.24

**Ex4:**If $8000 is invested for 6 years at a price 8% compounded continuously, find the new amount:P = $8000, r = 0.08, t = 6 years.A = 8000.e(0.08)(6) = 8000.(1.6160740) = $12,928.60

## Equivalent Value:

When a financial institution offers you an annual interemainder price of 6% compounded repeatedly, they are really paying you more than 6%. Since of compounding, the 6% is in fact a yield of 6.18% for the year. To watch this, take into consideration investing $1 at 6% per year compounded continuously for 1 year. The complete rerotate is:A = Pert = 1.e(0.06)(1) = $1.0618If we subtract from $1.618 the $1 we invested, the return is $0.618, which is 6.18% of the amount invested.See more: How Many Quarters Are In 5 Dollars ? How Many Quarters Are In 5 Dollars

The 6% annual interest rate of this instance is referred to as the

**nominal rate**The 6.18% is dubbed the

**reliable rate.**If the interemainder price is compounded

**continuously**at an annual interemainder rate r, then

**Effective interest rate: = er - 1**If the interest rate is compounded

**n times per year**at an yearly interest price r, then

**Effective interemainder rate = (1+r/n)n - 1**

**Ex5:**Which yield much better return:

**a)**9% compounded everyday or

**b)**9.1% compounded monthly?a) efficient rate = (1+0.09/365)365 - 1 = 0.094162b) efficient price = (1+0.091/12)12 - 1 = 0.094893the second price is better.

**Ex6:**An amount is invested at 7.5% per year compounded repeatedly, what is the effective yearly rate?the efficient price = er - 1 = e 0.075 - 1 = 1.0079 - 1 = 0.0779 = 7.79%

**Ex7:**A bank provides an effective rate of 5.41%, what is the nominal rate?er - 1 = 0.0541er = 1.0541r = ln 1.0541 then r = 0.0527 or 5.27%

## Present Value:

If the interest price is**compounded n times**per year at an annual price r, the present value of a A dollars payable t years from now is:

**If the interest rate is compounded continuously**at an yearly price r, the existing value of a A dollars payable t years from now is

### P = A. e-rt

**Ex8:**just how a lot need to you invest now at yearly price of 8% so that your balance 20 years from currently will be $10,000 if the interest is compounded a) quarterly: P = 10,000.(1+0.08/4)-(4)(20)= $ 2,051.10b) continuously: P = 10,000.e-(0.08)(20) = $2.018.97