- [Instructor] We've spent several videos
already talking about
graphs like you see here.
This is the graph for a particular firm,
maybe it's making donuts
so in the donut industry,
and we can see how the marginal cost
relates to the average variable
cost and average total cost.
We go into some depth several videos ago,
but we see that trend, that marginal cost,
can trend down initially
because as quantity increases
each incremental unit could benefit
from things like specialization.
And then the marginal cost,
the cost of each incremental
unit as a function of quantity could go up
because of things like coordination costs.
And then we've also seen
how that relates to average
variable costs, that while
marginal cost is below average
variable cost, every incremental
unit is going to bring
down the average variable
cost, but then when marginal
cost crosses average variable cost,
well now every incremental
unit is going to bring up
the average variable cost.
And the same thing happens once it crosses
the average total cost.
And of course the difference between,
for any given quantity,
between the average total cost
and the average variable cost,
that is the average fixed cost.
Now with that out of the way,
we're going to think about
how this firm would react under
different market conditions.
We're going to assume that
it's in a very competitive
or we could say a perfectly
competitive market
and so it is a price-taker.
And so let's first imagine
what would be a positive
scenario for this firm.
Let's imagine the price up
here, so let's call this P
sub-one and in a previous
video, we already said
it would be rational for
a profit-maximizing firm
to produce at a quantity
where the marginal cost
and the marginal revenue is meet.
And if we're talking about
a competitive market,
then this price right over
here is not going to be
a function of the firm's
quantity, so that's why
it's horizontal, and it
would be the same thing
as the marginal revenue.
So in this situation at P
sub-one, the firm would produce
Q sub-one, and this is a
good situation for the firm
because the price that
it's getting is higher
than its average total cost
and so there is going to be
a nice amount of profit for this firm.
The profit is going to be
the price minus the average
total cost at that quantity
times the actual quantity
so because P one is greater
than the average total cost,
we have a situation where
the firm is profitable,
firm is profitable, it would
want to stay in the market
but because you have a
profitable firm in this market
and you're likely to have
many profitable firms
in that market, it will
probably attract entrants.
Other people might say, hey,
I wanna make just as much
money as this donut
company right over here,
than this firm, and so you'll
probably have more and more
entrants into the market,
which will probably
reduce the prices.
Now they could reduce
the prices until you get
to a price that looks something like this.
So I will call that P sub-two.
Now, a profit-maximizing
firm in this world
would keep producing
until the marginal cost
is equal to the marginal
revenue, which in this case
is the price, and this would
be, my lines aren't completely
straight there but you get
the idea, so that's Q sub-two.
Now in this situation, P
sub-two is equal to the average
total cost, so the firm is break-even.
It's not running at a loss or a profit.
So it is break-even and so
here the firm is neutral
about whether in the long-run,
it stays in the market
or it exits the market,
but you're no longer
likely attracting entrants,
so no longer attracting,
attracting entrants.
But it does make sense for
the firm to keep operating
at this situation even in the long run
because it is at least break-even.
Now let's imagine another scenario,
let's imagine this price level.
So for whatever reason, the
market price gets to that
as we've talked about, a
rational firm would be producing
at Q sub-three, and at P
sub-three right over here,
there's some interesting things.
Because P sub-three is less
than your average total cost,
your firm is running at a loss,
it's running at a loss here.
So running, so firm, firm not profitable.
Not profitable.
Now you might say, well what
is this firm likely to do,
would it just shut down?
Well in the short-run,
it would not make sense
for this firm to shut
down because the price
that it's getting is still
higher than its average
variable cost, in the
short-run, the fixed cost,
they've already been
spent, so you might as well
get as much incremental profit
on the margin as you can
and so as long as the price
is higher than the average
variable cost, well outside
of their fixed cost,
they're still making some money
to make up those fixed costs
so you have two things going on.
So they would stay
operating in the short run,
stay operating, operating
in the short-run, short-run,
but what would this
firm do in the long-run?
Well in the long-run, it
makes no sense to have a,
to be in a market where
you can't make a profit
so in the long-run it
will exit, so it will exit
in the long-run.
And in general, the terminology
when people are talking
about, well, do you start
or stop in the short-run,
they usually talk about,
do you either shut down
or operate in the short-run,
and then in the long-run,
where it's like, hey, are you
going to sell your factories
or somehow dismantle them
or are you going to build
new factories, that's all
about exiting or entering
the industry.
And of course, you have
another even worse scenario
for this firm, which might be down here,
where you have price sub-four.
Here, in theory, this
is where we intersect
the marginal cost curve, Q sub-four.
Now here it makes no sense for the company
to operate at all, so
because P sub-four is less
than the average total
cost, you would want to exit
in the long-run, exit in
long-run, exit the market
but you wouldn't even wait for that long,
wait to sell your factories,
because P sub-four
is less than your average variable cost,
you would also just shut down,
shut down in the short-run.
So big picture from a
firm's point of view,
you obviously want to be at
P one where you make a profit
but you might attract entrants.
At P sub-two, you as a firm
in the long-run are neutral
versus exiting the market
or entering the market
or other people entering the
market, you're at breakeven.
At P sub-three, in the
long-run, you'd wanna exit
because you're not
profitable if the prices stay
at P sub-three, your price
is below your average
total cost at the rational
quantity to produce,
so in the long-run, you would exit.
But because P sub-three is
greater than your average
variable cost at the rational quantity,
you would stay operating in the short-run
and then the last scenario
of course is P sub-four
where the price gets so low
that it just doesn't make
sense to even operate another moment.
