Chapter 27 Flashcards
What is the time value of money?
• it’s all about how time works its magic on interest!
• Compounding: the accumulation of a sum of money where the interest earned on the sum earns additional interest -> you earn interest on the interest!
• example: suppose you put $1,000 in the bank today and leave it there for 30 years.
o if you earn interest of 8%, in 30 years, it will be worth $10,063
o if you earn interest of 10%, in 30 years, it will be worth $17,450
What are two flavors of time value of money problems?
• depends on whether we are looking: o •forward into the future, or
•backwards into the past.
• if we are trying to find out the value of $ held today at some time in the future -> future value of a present sum.
• if we pretend to be in the future and are trying to find out the value today
of $ held in the future -+ present value of a future sum.
• see http://bit.ly/10a0uyE (it’s a Khan Academy video)
Another look…
Another look.
• to compare sums from different times, we use the concept of
“present value” or “future value”
the present value of a future sum: the amount that would be needed today to produce that future sum at a certain interest rate.
• the future value of a sum: the amount that a sum of money NOW will be worth at some future date, when allowed to earn interest at a certain interest rate.
What are the two formulas you need to remember
• and four variables for each formula:
• PV = the amount of money you have today
• FV = the amount of money in the future
• n= the number of periods in the future (usually measured
in years)
•r = the interest rate
Every ‘time value of money’ problem uses these variables.
There are two formulas you need to remember
Future value - how much will a dollar held now be worth in year ‘n’?
general formula -> FV = PV * (1 + r)^n
example - if I put $1 in the bank today, and it earns interest of 10%:
• in one year, it would be worth [$PV x (1 + r )r] = 1 x (1.10)1 = $1.10
• in five years, it would be worth [$PV x (1 + r )n] = 1 x (1.10)5 = $1.61
There are two formulas you need to remember ..
Present value - how much is a dollar in year ‘n’ worth now?
FV
general formula -> PV = (1+7)n
example - if I want to have $1 in the bank in the future, and it will earn interest of 10% until then. How much will I need to deposit today?
• if I want the $1 one year from now, I must deposit today
FV/(1+r)n = 1/(1.10)1 = $0.9090 or 91¢
• if I want the $1 five years from now, I must deposit today
FV/(1+r)n = 1/(1.10)5 = $0.6209 or 62¢
What happens if we change the interest rate(r)?
° as interest rates rise, the present value of the project becomes
smaller.
• it works the other way, too -> as rates drop, PV rises!
• THIS IS A KEY FEATURE OF TIME VALUE OF MONEY.
• I’ll show some examples in a minute.
Present value analysis helps explain why investment falls when the interest rate rises.
What are the basic rules of thumb for PC analaysis
• greater weight is placed on earlier payments.
• the more ‘n’s there are (or the bigger the ‘n’), the higher PV will be.
• the higher the interest rate (‘r’), the lower PV will be.
o why? the higher PV means that later payments will be worth less, and so the sum of them will be lower. o riskier projects will have a higher ‘n’ which in turn means a lower PV -> they will be harder to justify. This makes sense.
What’s compounding
• Compounding: the accumulation of a sum of money where the interest earned on the sum earns additional interest -> you earn interest on the interest!
• because of compounding, small differences in interest rates lead to big differences over time.
• Compounding: the accumulation of a sum of money where the interest earned on the sum earns additional interest.
• example: Buy $1,000 worth of Microsoft stock, hold for 30 years.
If rate of return = 8%, FV = $10,063
If rate of return = 10%, FV = $17,450
The Rule of 7
• instead of the mathy formulas above, there’s a simple rule that
APPROXIMATES returns.
• the Rule of 70: If money grows at a rate of ‘x’ percent per year, that sum will double in about 70/x years.
• example:
• if interest rate is 5%, a deposit will double in about 14 years (70/5).
• if interest rate is 7%, a deposit will double in about 10 years (70/7).
What’s risk aversion?
° a key concept in psychology and behavioral economics
•there are lots of definitions. My favorite is finance based:
a risk averse person prefers lower returns with known risks rather than higher returns with unknown risks.
The basic idea: human beings don’t like risk and uncertainty and so they will take steps to avoid or reduce it.
What are the three types of people?
People are either
• risk averse - they avoid risk
•risk indifferent - they don’t care one way or the other
•risk seeking - they LIVE for risk
Risk aversion in real life
• most people are risk averse -they dislike uncertainty.
* example; suppose you are offered the following gamble -> I toss a fair coin (that is, it’s not rigged in my favor -> there is a 50% probability of the coin landing ‘heads’ or ‘tails).
o if it lands heads, you win $1,000. o if it lands ‘tails, you lose $1,000.
• should you take this gamble?
What is utility of wealth and diminishing marginal utility?
Utility of wealth is a subjective measure of vour happiness that depends on how rich vou are.
As wealth rises, the curve becomes flatter due to diminishing marginal utility: > the more wealth a person has, the less extra happiness he would get from an extra dollar of wealth.
How do people manage the
general financial risk they face every day?
With insurance!
• how insurance works -> a person facing a risk pays a fee to another person (usually an insurance company), which in return:
o accepts part or all of that risk by o agreeing to compensate the insured person if a loss occurs.
• having insurance changes people’s behavior.
Managing Risk with Insurance
• if you drive a car, you might get in an accident and cause damage to yourself or to others.
• you can accept all of the financial risk of an accident yourself. If you do this, you pay ALL the costs of an accident.
• insurance allows risks to be pooled -> the risk is “spread” among all the people the insurer insures.
• it’s better for 10,000 people to each bear 1/10,000 of the risk of someone’s house burning down than for one person to bear the entire risk alone.
• the people whose house DOESN’T burn down end up paying for the house that DOES burn down (through their premiums).
Everyone in the pool shares risks and costs.
• this “pooling of risks” can make a risk averse person better off.