DEMAND 
4£) 
the person pays a Id. for each apple, for the 
last penny which he is induced to spend on 
apples he obtains ten units of utility. So it is 
reasonable to affirm that the marginal utility 
of money to him contains ten units of utility. 
Because of the law.of equi-marginal returns 
another penny spent by him in anything else 
would buy only ten units of utility. For the 
twelve apples he pays twelve pennies, which 
consequently represent a sacrifice of 12 x 10 
units of utility, that is 120 units of utility. 
We may think of the 12 pence as withdrawn 
from expenditure on twelve other things, 
involving a marginal loss in respect of each 
of them amounting to ten units of utility. 
Now the total utility of twelve apples must 
be something considerably greater than twelve 
times their marginal utility, owing to the law 
of diminishing utility. If their total utility 
amounts to 210 units, the person whose case we 
are considering would enjoy a consumer’s sur 
plus of 90 units of utility, that is 210 minus 120. 
Another way of bringing out the meaning 
of this consumer’s surplus is to say that it 
represents the clear loss which would be 
sustained by the individual in question if he 
could have no apples. In such a case he 
would lose their total utility, 210 units, but 
against this he would have the utility got by