00:01
So here we're talking about elasticity, and in particular, the elasticity of demand.
00:07
Now, the definition for that is just something you need to know is the percentage change in quantity demanded over the percentage change in price.
00:15
That's just the definition of elasticity.
00:18
We're told that this is 3 .0, but really this is minus 3 .0, right? these are always negative.
00:29
We just drop the negative sign sometimes because we're lazy.
00:34
But these variables are inversely related, right? price goes up, quantity goes down.
00:39
These things have to be negative relationship, right? we just don't, when we write the elasticity, we just drop the negative sign because we know it's always got to be negative.
00:49
We know some information about the price.
00:53
We know the price went from six to four.
00:56
So the percentage change in the price is new, minus old over old, which is equal to minus two over six is equal to minus one -third.
01:09
So that would be the change in the price...