In: Economics
u (X,Y) = X3Y.
1. The utility is given to be
, and the budget line would be
. The MUs would be
or
or
and
or
or
. The optimal combination of goods would be where
or
or
. Putting it in the constraint, we have
or
or
, and since
, we have
. These are the demand for X and Y.
2. For the given prices and income, Randy's
optimal consumption of goods would be
or
and
or
.
3. For the new price of X, Randy's optimal
consumption of Y would not change and remain 25, but optimal
consumption of X would be
or
.
4. Randy's old utility level was
and new utility level is
. For the Marshallian demand of X be
and Y be c, the indirect utility level would be as
or
or
.
Now, for the indirect utility function be
, the inverse of this function
would be the expenditure function. Hence, from the indirect
utility function, we have
or
or
or
. This is the expenditure function. This is the expenditure
required for U* utils with prices Px and Py.
This means that for the old prices and new utility, the income
required is
or
or
or
. Hence, the equivalent variation would be 100-43.86 or $56.14.
This means that to reach the new utility a old price, the income
must be reduced by $56.14. The graph is as below.