Class 19 Sections 10 1 - 10 2 — Transcript
Full transcript
- 0:02hello
- 0:03and uh welcome to uh today's class
- 0:07uh which will cover sections 10.1
- 0:10and 10.2 uh which deals with
- 0:13inflation um and
- 0:17i'll go through you know the usual
- 0:19routine
- 0:20first you should start on the start here
- 0:22page on blackboard and
- 0:24and check out the assignments and
- 0:27because they do change from time to time
- 0:30and you should read pages 302 to 312 in
- 0:34your text that sec
- 0:35that covers these two sections um
- 0:40you will be watching this instructor
- 0:43video
- 0:44these lecture notes are critical to your
- 0:48success in the course
- 0:49and if you really want to be
- 0:52highly successful you need to work as
- 0:54many problems as you possibly can
- 0:57so we're going to talk about inflation
- 0:59now
- 1:00and
- 1:04how it impacts um the cost
- 1:08and and the the revenues and things like
- 1:11that which we deal with
- 1:14one of the most common well inflation
- 1:16refers to just
- 1:17simply the increase in cost
- 1:20over time to purchase goods and services
- 1:24um as an example
- 1:28of a service um if you bought an airline
- 1:32ticket and there
- 1:33and uh um the uh
- 1:38then you know a year later you bought
- 1:41that same
- 1:43uh type of ticket you're going to fly on
- 1:45the same
- 1:46type of aircraft you're going to fly the
- 1:48same route
- 1:50and it cost more well that would be
- 1:53an example of inflation in the cost of
- 1:56that
- 1:57service air travel
- 2:01if prices go down which they are
- 2:04with respect to air travel because of
- 2:06the pandemic
- 2:08then um that would be called deflection
- 2:13and and we're experiencing that for
- 2:15example with gas at the pump it's
- 2:17it's actually less now than it was maybe
- 2:2010 12 years ago
- 2:21so that's an example of deflation we
- 2:24rarely get deflation and it usually
- 2:26means something bad
- 2:28in this case it needs a pandemic is
- 2:30causing a decrease in the
- 2:33amount of oil
- 2:36needed to make the gasoline
- 2:39but inflation refers to the increase in
- 2:42cost
- 2:44of goods and services and that is a very
- 2:47common thing
- 2:49much more common than deflation
- 2:52a common measure of inflation is called
- 2:55the consumer price
- 2:57index actually it's a measure of
- 2:58inflation or deflation
- 3:01and the consumer price index
- 3:04is a is a measurement kept by the the
- 3:07federal government the bureau of
- 3:09statistics uh economic statistics and
- 3:13they
- 3:14publish a new number every month and so
- 3:17there's a yearly inflation
- 3:19rate and a monthly inflation rate and
- 3:23the consumer price index basically
- 3:26consists of a number of
- 3:30commonly used goods and services
- 3:34as an example food energy transportation
- 3:38health care
- 3:39and housing are all part of the consumer
- 3:42price index
- 3:43and what they look at is what is a an
- 3:46american
- 3:47family usually buy and then has that
- 3:50gone
- 3:51up in the last month uh if we take a
- 3:53weighted average of those things
- 3:56and and so equation 10.1
- 3:59tells us that the the dollars in period
- 4:03t1
- 4:04equals the dollars in period t2 now this
- 4:07is where t2 is in the future from t1
- 4:11times 1 plus the inflation from
- 4:14t1 to t2 from time 1 to time 2.
- 4:18so um i'm sorry it's not times it's
- 4:23divided by
- 4:25there's a slash there okay divided by
- 4:281 plus the inflation now this does not
- 4:31say the inflation rate this is the
- 4:34entire amount of inflation from time 1
- 4:36to time
- 4:372. and we're taking the dollars in
- 4:40period 2
- 4:41and basically dividing by 1 plus the
- 4:44inflation rate between those periods
- 4:46gives us the the dollars
- 4:49at time 1. so we can use this equation
- 4:53for example we could multiply through
- 4:55this equation
- 4:56through the the the thing we're dividing
- 4:59by 1 plus the inflation
- 5:01if we multiply through the equation we
- 5:03can put the
- 5:05dollars at time 2 in terms of the
- 5:08dollars at time
- 5:09one um and um
- 5:12in this case we're kind of deflating the
- 5:14dollars at time
- 5:16two because we're dividing by this if we
- 5:19were to multiply through by one plus the
- 5:21inflation
- 5:22and and um get
- 5:25t2 in terms of t1 then we
- 5:28we would be inflating from t1 to t2
- 5:33um the term
- 5:37constant value dollars refers to
- 5:40um what the dollars are worth
- 5:44now what they could buy now um
- 5:47as opposed to what they what
- 5:50what it'll cost say in the future to do
- 5:54something like that so equation 10.2
- 5:57says constant value dollars
- 5:59equals future dollars divided by 1
- 6:02plus the inflation rate little f
- 6:05is the is a term that's analogous to the
- 6:09i that we've been using for interest
- 6:11rate
- 6:12it's analogous to that it's a rate and
- 6:15we
- 6:15we divide the future dollars by one plus
- 6:19uh the inflation rate to the
- 6:21nth power if there are n periods between
- 6:25the the the current time and the future
- 6:28time
- 6:30okay so this is just kind of another
- 6:33statement of this
- 6:35but it does it by period because f
- 6:38is a rate as opposed to a total amount
- 6:41of inflation
- 6:44if we solve equation 10
- 6:472 for future dollars we simply multiply
- 6:51through by 1 plus
- 6:52f to the n we get future dollars
- 6:55equals the constant value dollars times
- 6:581
- 6:58plus f to the nth power so in this
- 7:02case we're inflating the constant value
- 7:04dollars
- 7:05to get them out to the future this works
- 7:08just like
- 7:08f given p and p given f uh but
- 7:11now it's not the interest that's being
- 7:16that's causing the value to increase
- 7:18it's the inflation rate
- 7:20um so i have a lot of experience with
- 7:25this in
- 7:25in the aircraft industry and in the
- 7:29design of an airplane
- 7:31there may be a long period of time
- 7:33between
- 7:34the the time when you're designing the
- 7:37airplane and you're doing production
- 7:39cost estimates and when the actual
- 7:42airplane is going to be produced because
- 7:44with aircraft especially
- 7:48advanced aircraft if we want to call
- 7:50them that
- 7:52there's usually after the design phase
- 7:55there's you build a prototype you test
- 7:59the prototype
- 8:00build several of them actually so you
- 8:03build several airplanes you test the
- 8:05prototype
- 8:08with test pilots and they give you
- 8:11feedback
- 8:12you redesign and so on so there could be
- 8:15what i'm saying here is there could be
- 8:17as many as 10 or more years between the
- 8:19early designs
- 8:21and the final
- 8:24start of the production of the airplane
- 8:27as a
- 8:28as a unit so during that period of time
- 8:32inflation is occurring and very often
- 8:35then
- 8:36what you estimated the production cost
- 8:38would be has to be inflated
- 8:41then um up to get the true cost
- 8:45when the aircraft is actually going to
- 8:47go
- 8:48into production uh maybe 10 or 12 years
- 8:51later
- 8:52so this is what what we did we we
- 8:55basically used this
- 8:57uh this equation 10.3 to
- 9:00inflate what it would cost now to build
- 9:02that airplane which would be called
- 9:04constant value dollars
- 9:07times one plus the inflation rate
- 9:09actually we
- 9:11we didn't just use for example the
- 9:12consumer price index for the inflation
- 9:15rate
- 9:15we broke the airplane down into into
- 9:18major
- 9:18subsystems and and each of those had a
- 9:21different
- 9:22inflation rate and so we would apply
- 9:24that to the subsystems and then
- 9:26i add it all up but the bottom line is
- 9:28we were using this
- 9:30all the time because of the lar long
- 9:33time
- 9:33frame of our projects
- 9:36um so um
- 9:39[Music]
- 9:41i want to get into some some definitions
- 9:44so we call
- 9:45constant value dollars uninflated
- 9:48dollars
- 9:49if we want to inflate them one with the
- 9:52inflation rate
- 9:53f for n periods then that gives us
- 9:56future dollars and um if you recall
- 10:01the uh the
- 10:04rate i that we've been using throughout
- 10:07the semester we really didn't talk about
- 10:09inflation until this chapter
- 10:11actually we're not going to talk about
- 10:12it again after this chapter but
- 10:15um we used uh the real
- 10:18rate or the inflation-free interest rate
- 10:22i so that i that we've been using
- 10:26um theoretically is the inflation-free
- 10:30interest rate well there's another rate
- 10:33that we call the adjusted rate
- 10:36inflation adjusted rate which is i
- 10:40sub f so the i sub f
- 10:44includes inflation and this
- 10:48is also called the market rate that's
- 10:51the most common term
- 10:52to use this affliction adjusted rate
- 10:55market rate
- 10:56is i sub f okay
- 11:00and that rate includes
- 11:03both the increase in price due to
- 11:06inflation
- 11:07plus the increase due to
- 11:10time and the interest rate i so um
- 11:14we'll we'll talk about that relationship
- 11:18here and some other equations but
- 11:20um the next chapter
- 11:24the author actually defines the market
- 11:27rate
- 11:28i sub f equals to
- 11:31i that's the real rate
- 11:34real interest rate plus f the inflation
- 11:38rate
- 11:38plus the product of those two i times f
- 11:42so equation 10.4
- 11:45in section 10.2
- 11:48which tells us how to adjust our
- 11:51calculations
- 11:52to account for inflation if we have some
- 11:55future dollars then
- 11:58we need to divide that by one plus
- 12:01f to the nth power that
- 12:05takes out the inflation so then i'll
- 12:08have constant value
- 12:10dollars here and then i divide that by 1
- 12:12plus
- 12:13i to the n which takes out the time
- 12:16value of money and so
- 12:19if we multiply these two quantities
- 12:22together
- 12:23we get this should be a
- 12:27capital f here
- 12:32we get f times 1
- 12:36plus i plus f plus i f all i've done is
- 12:39multiply
- 12:40to the nth power and um
- 12:43so that is equation 10.4
- 12:47and then um uh so
- 12:50by dividing by 1 plus f to the n
- 12:54that adjusts for inflation then you're
- 12:56dividing by 1 plus i to the n
- 12:59and that adjusts for the real interest
- 13:01rate and
- 13:02um we call the quantity
- 13:05that is i plus f plus i f we call that
- 13:08the market rate
- 13:09and um if we take 1 plus
- 13:12i sub r i sub r i'm sorry
- 13:16i sub f recall is the inflation rate i'm
- 13:20sorry the market rate
- 13:21uh and that's equal to one plus i
- 13:25times one plus f which is one plus
- 13:28i plus f plus i f and if we subtract one
- 13:31from both sides
- 13:33we get equation six that is the market
- 13:36rate
- 13:36i sub f equals the interest rate the
- 13:40real rate
- 13:42plus the inflation rate plus the product
- 13:45of the interest rate
- 13:46and the inflation rate and then if we
- 13:49substitute
- 13:50equation 6 into equation 4 here you can
- 13:54see that what we're going to get there
- 13:56we get that p is equal to capital f
- 13:59times 1 plus
- 14:00i sub r to the n i'm sorry divided by 1
- 14:04plus
- 14:04i to the i sub f to the
- 14:08n which is the same thing as
- 14:11f p given f i sub f
- 14:15and n okay so that's equation
- 14:18five uh we kind of went backwards there
- 14:21but
- 14:21but i needed this equation to plug into
- 14:24this
- 14:25to get me to this um
- 14:28and then there's a an example of if the
- 14:32real interest rate i is six percent
- 14:35and the inflation rate f is four percent
- 14:39then the market or inflation adjusted
- 14:42rate i sub f is six percent
- 14:47plus four percent plus the product which
- 14:49would give me
- 14:50you know this is going to be 0.0024
- 14:53which would give me 10.24 percent
- 14:57so we're going to do an example of
- 15:00looking at what would happen to
- 15:03a lottery winner who has three
- 15:07options on collecting your money that
- 15:10would be nice to be a lottery winner i
- 15:12suppose
- 15:13um although i don't think many of them
- 15:15have been
- 15:16more happy after they get it anyway
- 15:20um here's the situation
- 15:23um the the
- 15:26the lottery the lottery winner can take
- 15:29their winnings in one of three ways and
- 15:33he says f is equal to the inflation
- 15:35rates four percent
- 15:36and the interest rate is six percent so
- 15:38that's a uh that will give us
- 15:40a a market rate which is the product of
- 15:44these
- 15:44two plus each one uh is going to be
- 15:4810.24 percent so
- 15:50you can either take these are your
- 15:52options three options
- 15:54uh the red option is to take a hundred
- 15:57thousand right now
- 15:58the blue option number two is to take
- 16:01eight payments of fifteen thousand
- 16:03that's
- 16:04uh each uh starting one year from now
- 16:07well that's
- 16:08just an a series right uh of fifteen
- 16:11thousand dollars for
- 16:12eight years and then there's a third
- 16:14option this is the green
- 16:16option which is forty five thousand now
- 16:19forty five thousand
- 16:20after four years and another forty five
- 16:23thousand
- 16:23after eight years so let's look at what
- 16:27is the present value of each of those
- 16:30using the market rate which is ten point
- 16:32two four percent
- 16:34which we we found that on the previous
- 16:36page
- 16:38well the present value of this one is
- 16:41just a hundred thousand dollars
- 16:42of course we're gonna forget about
- 16:44income taxes for now
- 16:46um the present value of plan two which
- 16:49is an a
- 16:50series of fifteen thousand is fifteen
- 16:52thousand p
- 16:53given a um the market rate
- 16:56for eight periods that's seventy nine
- 16:58thousand
- 16:59um three hundred and twenty nine dollars
- 17:02and the third option forty five thousand
- 17:05now forty five thousand four years and
- 17:07forty five thousand in eight years
- 17:09if you plug in and um the forty five
- 17:12thousand now is worth forty five
- 17:14thousand that's why there's a one here
- 17:16and then the forty five thousand four
- 17:18years from now you have to multiply it
- 17:20on p
- 17:21given f ten point two four percent for
- 17:23four years
- 17:24and then the eight years will be
- 17:26multiplied by p
- 17:27given f ten point two four percent for
- 17:30eight years
- 17:31if you do that multiplication you get
- 17:33ninety six thousand
- 17:34and ninety nine dollars so the best
- 17:37option is to take your hundred thousand
- 17:39dollars now
- 17:41of course that is before income taxes so
- 17:46the outcome after income taxes might be
- 17:48a little bit different
- 17:49and we'll learn a little bit about
- 17:52income taxes in chapter 13
- 17:54but for now i want to just
- 17:58look at a couple of problems just to
- 18:00solidify this theory
- 18:03the first problem example problem that
- 18:05i'm going to
- 18:06talk about here is
- 18:09in an inflationary period the dollar
- 18:11based currency
- 18:13what is the difference between inflated
- 18:16dollars
- 18:16and then current dollars okay there is
- 18:20on inflated dollars and then
- 18:23current dollars remember there is no
- 18:26difference
- 18:27inflated dollars are then current
- 18:30dollars
- 18:30they're also called future dollars i i
- 18:33forgot to mention that in a lecture
- 18:35that they are called then current
- 18:37dollars
- 18:38okay so there's no difference and and
- 18:41then i go on to say in industry we refer
- 18:44to
- 18:44inflated dollars as future dollars uh
- 18:48or future dollars as during current
- 18:50dollars
- 18:51um part b
- 18:54what is the difference between then
- 18:56current dollars
- 18:58future dollars and constant value
- 19:00dollars well remember that was one of
- 19:02our equations
- 19:03to convert from future dollars to
- 19:06constant value dollars
- 19:07and vice versa that those were equations
- 19:11two
- 19:11and three in in chapter ten
- 19:15so the difference between then current
- 19:17future dollars
- 19:19and constant value dollars is that then
- 19:22current dollars include inflation and
- 19:25constant value dollars do not
- 19:28this is expressed by equations 10.2
- 19:32and 10.3 constant value dollars equals
- 19:36future dollars divided by
- 19:38one plus the inflation rate to the nth
- 19:40power
- 19:41dividing by one plus the inflation rate
- 19:43to the nth power removes inflation
- 19:47okay future dollars eq constant value
- 19:49dollars times
- 19:50times 1 plus the inflation rate to the
- 19:53nth power
- 19:54multiplying by 1 plus the inflation rate
- 19:57to the n power
- 19:58adds inflation so that's how we do it
- 20:01notice that this
- 20:02is exactly the same as interest rates
- 20:05and future worth and present worth
- 20:07uh only when when we were doing that we
- 20:10used
- 20:11the rate i the interest rate now we're
- 20:14using the rate
- 20:16f the inflation rate
- 20:20okay this will be the last part of
- 20:22today's uh
- 20:23lesson um this is example
- 20:27two um according to the data of the
- 20:31national association of colleges
- 20:33colleges and employers engineering
- 20:37graduates
- 20:38average starting salary of 61
- 20:42872 dollars were among the highest of
- 20:45all majors
- 20:46of the class of 2011.
- 20:51what will be the average starting salary
- 20:53amount
- 20:54uh in 2019 if salaries increase at the
- 20:59rate of 2
- 21:00per year so let's look at that part
- 21:03using uh equation 10.3
- 21:07uh and f equals two percent we get
- 21:10f the future value
- 21:13uh in 2019 equals p
- 21:16well which is really constant value
- 21:18dollars 20
- 21:2011 times one plus the uh
- 21:23inflation rate to the nth power and of
- 21:25course that inflation rate is two
- 21:27percent so
- 21:28f 2019 is equal to
- 21:3161 872 that's essentially constant value
- 21:37dollars or present dollars
- 21:391.02 to the eighth power gives us 72
- 21:45493. um
- 21:49part b what if uh
- 21:52the inflation rate of
- 21:55of uh is twice the inflation what if the
- 21:59the rate of increase of salaries
- 22:02is twice the inflation rate of three and
- 22:05a half percent so
- 22:06two times three and a half percent at
- 22:08seven percent so it's
- 22:09asking you what will the future
- 22:13average starting salary be if
- 22:17they went up by seven percent per year
- 22:20so the future value in 2019
- 22:23is the constant value p in 2011 times
- 22:27one plus
- 22:28f to the eighth power again but now
- 22:31the f is seven percent so when we
- 22:34multiply
- 22:35um sixty one thousand eight hundred and
- 22:38seventy two one
- 22:39times 1.07 to the 8th power we get
- 22:43106 308.
- 22:46so that concludes today's lesson
- 22:49on sections 10.1 and 10.2
- 22:52thank you
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