assuming you meant Quilting.
since there are 4 students in her class, that'd be the first term, and then the 4 students each teaches another 4 students, and so on, so the amount of folks who'd know quilting will be
4, 16, 64, ....
where the "common ratio" r = 4, and a₁=4
[tex]\bf \qquad \qquad \textit{sum of a finite geometric sequence}
\\\\
S_n=\sum\limits_{i=1}^{n}\ a_1\cdot r^{i-1}\implies S_n=a_1\left( \cfrac{1-r^n}{1-r} \right)\quad
\begin{cases}
n=n^{th}\ term\\
a_1=\textit{first term's value}\\
r=\textit{common ratio}\\
----------\\
a_1=4\\
r=4\\
n=5
\end{cases}
\\\\\\
S_5=4\left( \cfrac{1-4^5}{1-4} \right)\implies S_5=4\left( \cfrac{-1023}{-3} \right)\implies S_5=1364[/tex]
