If
disposable income Yd desired consumption "C" average propensity to
consume APC=
C/Yd
--------------------------- ----------------------------- ---------------------------
o 100
100 180 1.800
400 420
change in "C"=420-180= 240
change in "y"= 400-100= 300
marginal propensity to consume= change in"C"/CHANGE IN"Y"=
240/300=O.80