In: Economics
Consider the following utility function: u(x, y) = x2/3y1/3. Suppose that Px = 4, Py = 2 and the income is I = 30. Derive the optimal choice for both goods.
The utility function is given as
, prices are
and
, while income
.
The the optimal choice for goods x and y is where given the
budget constraint, utility is maximized. Budget constraint can be
arranged as
, assuming all income is exhausted on the commodities. Hence, we
have
as the budget constraint. We will optimize the problem with
Lagrangian multiplier.
The problem is
subject to
.
The lagrangian function is hence,
. We will do partial differentiation with respect to lambda, x and
y.
or
or
. Equating
, we have
or
, the constraint itself.
or
or
or
. Equating
, we have
or
or
.
or
or
or
. Equating
, we have
or
or
.
Equating the last two lambda's, we have
or
or
or
or
.
Putting the value in the constraint, we have
or
or
; and
or
or
.
Hence, the optimal choice of
maximizing the given utility in the given budget constraint is
, ie 5 units of x and 5 units of y.