For the answer to the question above,
we must use this formula,
(New - Old)/ (Ave. of New and Old)
In this case,
501k -500k/(500,500(which is the ave. of the two.
Then it would be 1k/500,500
Then the answer would be .0020
Then
-1.439.5/439.5 because this is the average of the two.
so the answer would be .0023
Then finally divide the rate on change of quantity by the rate of change in price which is
0.002/-0.0023
Then the answer would be -.87
So the elasticity on the demand of model T is .87 ( remove the negative because elasticity is always positive.)