00:01
Okay, so we have the price of phones going down, quantity going up.
00:05
We're told the demand curve hasn't shifted, so we're moving along the demand curve.
00:09
And we're told that the total expenditure, which is price times quantity, goes up.
00:19
This is almost a definitional thing, and the answer is that demand is elastic.
00:28
Elastic demand or elasticity of demand refers to the responsiveness of quantity to price.
00:35
And if quantity responds more in percentage terms than price, then it's elastic.
00:43
But i'll show you how you can kind of show this algebraically as well.
00:50
So if you think of our new position, we have price plus the change in price, quantity plus a change in quantity...