I need to review sets for my probability and statistical inference course.

I do not understand the meaning of the following:

$\displaystyle

\begin{gathered}

A_k = \left\{ {x:\frac{{10}}

{{k + 1}} \leqslant x \leqslant 10} \right\},k = 1,2,3,.... \hfill \\

\hfill \\

\bigcap\limits_{k = 1}^8 {A_k } = \left\{ {x:5 \leqslant x \leqslant 10} \right\} = A_1 \hfill \\

\end{gathered}

$