Suppose n = 22 = 5(4) + 2. Computing the first quartile as defined above gives (n+1)s = 23(0.25) = 5.75 = 5 + 0.75 = m + r. Therefore,
\begin{equation*}
Q_1 = 0.25 \times y_5 + 0.75 \times y_6
\end{equation*}
which is a value closer to \(y_6\text{.}\) Many graphing calculators however quickly approximate this with
\begin{equation*}
0.5 \times y_5 + 0.5 \times y_6
\end{equation*}
so you should be aware of this possible difference. You should also notice that in this case s = 0.25 but r = 0.75 so these values are not required to be the same.