Find S when ¯C=200, MPC=0.4 and Y=1,000.
We know that, S=−¯S+MPC(Y)
We also know that saving is negative to the extent where consumption is positive, when Y=0.
So that −¯S=−200
Substituting the given values, we get:
S=−200+0.4(1,000)
=−200+400=200