Quadratic Vertex Word Problems

A couple of dance groups on campus decide to put on a performance. They start the ticket sale $2$ weeks before the show. On the first day, they sold tickets for $8$ hours.

Let $x$ be the time—for example, if $x$ is $2$, it is the second hour of sale. Let $y$ be the number of tickets sold in any given hour. The relationship between $x$ and $y$ is roughly:

$$y=-2\left(x-1\right)\left(x-8\right)$$

Assume that $0\leq x\leq8$.