International Economics : Finance Solutions To Problem Set 2
Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit
International Economics : Finance
Solutions To Problem Set 2
Question 1
(Exercise 6.3, SUW)
1. The household
problem
is simply:
maxC1,C2,B1 s.t
ln(C1) + I ln(C2)
C1 + C2 = Q1 + Q2
Using the optimality condition we solve for the optimal allocation as follow:
U1(C1, C2) 1 C1 C2 |
=
=
= |
(1 + r)U2(C1, C2) 1 C2 C1 |
From the intertemporal budget constraint we get:
C2 = C1 = 10
Now we simply compute the desired variables using the following equations:
B1 = Q1 _ C1 = 0
TB1 = Q1 _ C1 = 0
CA1 = TB1 + rB0 = 0
2. Expected endowment in period 2 = 0.01(1) + 0.99() = 10
This is the same expected endowment as in period 1. However, while the period 1 endow- ment was certain, the period 2 endowment can take one of two different values depending on the state. Hence, it is a mean preserving spread of the period 1 case.
3. Consider the household’s budget constraints. From each budget constraint we can obtain an expression for consumption as follows:
Period 1: C1 + B1 = 10 → C1 = 10 _ B1
Period 2 - Bad state: C2 = B1 + 1 Good state: C2 = + B1
Therefore expected lifetime utility is given by:
ln(10 _ B1) + 0.01 ln(B1 + 1) + 0.99 ln ╱ + B1、
Now simply differentiating with respect to B1 we can solve for optimal savings as follows:
+ + = 0
from this we get two solutions for B1 = f0.295147, _1.38606} we choose B1 = 0.295147 since we know the problem is such that for the household is optimal to save in the first period due to the uncertainty they are facing then have B1 > 0 is optimal. We follow the same logic for the solution in part 5.
Percentage of endowment exported is = x 100 = 2.95147.
Note since there is uncertainty as to the endowment in period 2, the household is simply saving now (where as they didn’t save under certainty) in order to insure against the pos- sible realization of the bad state in period 2 and smooth consumption over both periods. For comparison with later parts of this exercise we also compute period 1 consumption in this case:
C1 = 10 _ B1 = 9.704853
4. Mean endowment in period 2 = 0.02(1) + 0.98() = 9.909
Standard deviation = ′0.02(1 _ 9.909)2 + 0.98( _ 9.909)2 = 1.2727
Since the mean of the period 2 endowment has decreased, the change in probability is clearly not mean preserving.
5. Following the same steps as we did in part 4 we get the following expected lifetime utility function:
ln(10 _ B1) + 0.02 ln(B1 + 1) + 0.98 ln ╱ + B1、
Now simply differentiating with respect to B1 we can solve for optimal savings as follows:
+ + = 0
B1 = 0.521069 = TB1
C1 = 10 _ B1 = 9.478931
6. Since the probability of the bad state has increased, the household needs to save more in order to insure against the bad state and smooth consumption over both periods. Con- sequently, this higher savings implies lower consumption in period 1.
Question 2
(Exercise 5.4 parts 1-7, SUW)
Note: I use A1 = 3 + for the solution, but if you use A1 = 1 in your solution no point will be taken out.
1. I0 is given then we compute profits and production by
Q1 = A1I0(a) =
I1 = A1I0(a) _ (1 + r0 ) I0 = _ (1 + 0.25) 16 = 6 +
2. For period 2 we need to solve for
max A2I1(3/4) _ (1 + r1 ) I1
I1
then optimality condition is A2aI1(a) _1 = (1 + r1 )
as there is free capital mobility then r1 = r* = 0.2, A2 = 3.2 and a = 3/4. Then I1 = 16 so output and profits are
Q2 = A2I1(a) = 25.6
I2 = 25.6 _ (1 + 0.2) 16 = 6.4
3. Households solve the following problem
max ln C1 + ln C2
C1,C2
subject to
C1 + = (1 + r0 ) B0(h) + I1 +
then optimality conditions
= (1 + r1 )
C2 = (1 + r1 ) C1
combining with the budget constraint
2C1 = (1 + r0 ) B0(h) + I1 +
C1 = (1 + 0.25) 8 + 6 + + = 11
2
then C2 = 13.2.
4. Using the identities in the class notes
TB1 = Q1 _ C1 _ I1 = _ 11 _ 16 = _
CA1 = TB1 + r0 ╱ B0(h) _ I0、= _ + 0.25 (8 _ 16) = _2 _ = _2.
S1 = Q1 _ C1 + r0 ╱ B0(h) _ I0、= _ 11 + 0.25 (8 _ 16) = 13 + = 13. we can get B1(h) by using
C2 = (1 + r1 ) B1(h) + I2
B1(h) = = = 5 +
then
B1(*) = B1(h) _ D1 = 5 + _ 16 = _ ╱ 10 + 、
5. Now the interest rate r1 = 0.5 then investment solves
A2aI1(a) _1 = (1 + r1 )
I1 = 6.5536
and profits in the second period are
I2 = A2I1(a) _ (1 + r1 ) I1 = 3.2768
both reduced since more costly to finance at higher rates. Now household consumption is
C1 = (1 + 0.25) 8 + 6 + + = 9.4256
2
C2 = (1 + r1 ) C1 = 14.1384
consumption is reduced first period and even though profits in 2 lower slighlty increased in C2 to compensate for low consumption in 1. Next, we can compute the trade balance, current account and savings
TB1 = Q1 _ C1 _ I1 = _ 9.4256 _ 6.5536 = 10.68746
CA1 = TB1 + r0 ╱ B0(h) _ I0、= 10.68746 + 0.25 (8 _ 16) = 8.6874
S1 = Q1 _ C1 + r0 ╱ B0(h) _ I0、= _ 9.4256 + 0.25 (8 _ 16) = 15.241
and
C2 = (1 + r1 ) B1(h) + I2
B1(h) = = = 7.241
then
B1(*) = B1(h) _ D1 = 7.241 _ 6.5536 = 0.6874
the increase in interest rates at period 1, i.e. r1, contracts sharply investment since now is more costly to finance it. Moreover, consumption in period 1 is reduced as there are more return on savings now, still consumption in 2 increase but slighlty less than the reduc- tion of consumption in 1 since profits in period 2 where reduced. Trade balance, current account and savings increase in 1 as a consequence of the greater returns of delaying con- sumption now, and cost of invest. Further, this improves the net foreign asset position at period 1.
6. Now productivity in 1 is A1 = 4 and r1 = 0.2. Investment in period 1 and profits in period 2 are
I1 = 16
I2 = 6.4
as in part 2. Profits and production in 1 increase to
Q1 = A1I0(a) = 32
I1 = A1I0(a) _ (1 + r0 ) I0 = 32 _ (1 + 0.25) 16 = 12
then consumption of the households is now
C1 = (1 + 0.25) 8 + 12 + = 13 + 2
C2 = (1 + r1 ) C1 = 16.4
then
TB1 = Q1 _ C1 _ I1 = 32 _ ╱ 13 + 、 _ 16 = 2 +
CA1 = TB1 + r0 ╱ B0(h) _ I0、= 2 + + 0.25 (8 _ 16) =
S1 = Q1 _ C1 + r0 ╱ B0(h) _ I0、= 32 _ ╱ 13 + 、 + 0.25 (8 _ 16) = 16 +
the intuition is that an increase in productivity in 1 translates in an increase in profits in 1, therefore the permanent income of households increase which increase consumption in 1 and 2. Moreover, as this increase in productivity is transitory then savings need to increase, same as the current account and trade balance.
7. Now we assume A1 = 3 + and A2 = 4 then investment at period 1 solves
A2aI1(a) _1 = (1 + r1 )
I1 = 39.0625
and profits at 2
I2 = A2I1(a) _ (1 + r1 ) I1 = 15.625
then consumption of household are
C1 = (1 + 0.25) 8 + 6 + + = 14.84375
2
C2 = (1 + r1 ) C1 = 17.8125
then
TB1 = Q1 _ C1 _ I1 = _ 14.84375 _ 39.0625 = _27.2396
CA1 = TB1 + r0 ╱ B0(h) _ I0、= _27.2396 + 0.25 (8 _ 16) = _29.2396 S1 = Q1 _ C1 + r0 ╱ B0(h) _ I0、= _ 14.84375 + 0.25 (8 _ 16) = 9.82
the intuition is that even though nothing happens in the first period, and anticipated in- crease in productivity increase profits tomorrow, thus investment today. Not only this the increase in profits increases the permanent income of housholds which now are going to be able to consume more in both periods. As a consequences of consumption smooth- ing and increase in investment we have that savings, trade balance and current account deteriorate.
Question 3
(Exercise 7.2, SUW)
We assume U.S. is a large economy, while El Salvador a small one. An improvement in the grain production due to better weather can be interpreted as an increase in productivity today, this increase profits of firms in U.S. today. Assuming the shock is transitory the savings of the households will increase today for consumption smoothing reasons. This shifts the current account curve to the right and down, which reduces the international
interest rate and increments the current account of U.S..
r
CARowCAt$
On the other hand, El Salvador is a small open economy, then takes as given the interest rate. So a decrease in the interest rate, coming from the supply shock in U.S., will make El Salvador want to borrow relatively more therefore reduce their CA balance.
r
CAES
r*
rn(*)ew
CAnew CA
CAES
Question 4
(Exercise 7.4, , SUW)
1. First, lets solve for consumption allocation for the US. From the optimality condition we have:
U1(C1(U), C2(U))
1
CU
C2(U)
= (1 + r)U2(C1(U), C2(U))
= (1 + r)
= (1 + r)C1(U)
Plugging this into the intertemporal budget constraint, we have:
C1(U) + = 10 +
C1(U) = 0.5 ┌ 10 + ┐
From here we find the US period 1 current account:
CA 1(U) = 10 _ C1(U) = 5 _
In the same way we also find the period 1 consumption and current account for Europe, and since both economies have the exact same preferences and endowment, we get the same allocation:
C1(E) = 0.5 ┌ 10 + ┐
5
1 + r
Now market clearing implies:
C1(E) + C1(U) = Q 1(U) + Q1(E)
0.5 ┌ 10 + ┐ + 0.5 ┌ 10 + ┐ = 20
=÷ r = 0
So we have:
C1(U) = C2(U) = C1(E) = C2(E) = 10
CA 1(E) = CA2(U) = 0
2. Note, since the endowment of Europe is unchanged, Europe’s period 1 consumption as a function of the interest rate us unchanged,
C1(E) = 0.5 ┌ 10 + ┐
Now with the change in the period 1 endowment, the US period 1 consumption level as a function of the interest is now:
C1(U) = 0.5 ┌8 + ┐
Now market clearing implies:
C1(E) + C1(U) = Q 1(U) + Q1(E)
0.5 ┌ 10 + ┐ + 0.5 ┌8 + ┐ = 18
=÷ r = = 0.1111
So we have:
CA 1(U) = Q 1(U) _ C1(U) = 8 _ 0.5 ┌8 + ┐ = _0.5
CA 1(E) = Q 1(E) _ C1(E) = 10 _ 0.5 ┌ 10 + ┐ = 0.5
In the first type of contraction, the US expected a lower endowment in the first period and so to smooth consumption they dissave in period 1, and this decrease of savings drives up the interest rate.
3. Just as before, Europe’s period 1 consumption as a function of the interest rate us unchanged,
C1(E) = 0.5 ┌ 10 + ┐
The US period 1 consumption level as a function of the interest is now:
C1(U) = 0.5 ┌8 + ┐
Now market clearing implies:
C1(E) + C1(U) = Q 1(U) + Q1(E)
0.5 ┌ 10 + ┐ + 0.5 ┌8 + ┐ = 18
1
9
So we have:
CA 1(U) = Q1(U) _ C1(U) = 8 _ 0.5 ┌8 + ┐ = 0.625
CA1(E) = Q1(E) _ C1(E) = 10 _ 0.5 ┌ 10 + ┐ = _0.625
In the second type of contraction, the US expected a lower endowment in the second period and so to smooth consumption they saved in period 1, and this increase in demand for savings drove down the interest rate.
4. As can be learned from the previous part, a fall in the interest rate is a result of increased savings. Hence, the model would conclude that people expected a sharp fall in their future endowments and a significant decline in real activity and so they drastically increased their savings which pushed down the interest rate.
2022-03-09