The prices of the 19 top-rated all-season tires for a specific tire size, are as follows. Answer parts (a) - (c)
\begin{tabular}{lllllllllll}
$\$ 87$ & $\$ 118$ & $\$ 98$ & $\$ 79$ & $\$ 82$ & $\$ 90$ & $\$ 91$ & $\$ 89$ & $\$ 91$ & $\$ 81$ & $\square$ \\
$\$ 109$ & $\$ 114$ & $\$ 101$ & $\$ 95$ & $\$ 86$ & $\$ 90$ & $\$ 75$ & $\$ 99$ & $\$ 90$ & &
\end{tabular}
a) Determine $\mathrm{Q}_{2}$.
\[
\mathrm{Q}_{2}=\square
\]
b) Determine $Q_{1}$.
\[
Q_{1}=\square
\]
c) Determine $\mathrm{Q}_{3}$.
\[
Q_{3}=\square
\]

Step 1 ：First, arrange the data in ascending order: \(75, 79, 81, 82, 86, 87, 89, 90, 90, 90, 91, 91, 95, 98, 99, 101, 109, 114, 118\)

Step 2 ：To find Q2, find the median of the entire data set. Since there are 19 data points, the median will be the 10th value. So, \(Q2 = 90\)

Step 3 ：To find Q1, find the median of the lower half of the data. The lower half of the data is: \(75, 79, 81, 82, 86, 87, 89, 90, 90\). Since there are 9 data points, the median will be the 5th value. So, \(Q1 = 86\)

Step 4 ：To find Q3, find the median of the upper half of the data. The upper half of the data is: \(90, 91, 91, 95, 98, 99, 101, 109, 114, 118\). Since there are 10 data points, the median will be the average of the 5th and 6th values. So, \(Q3 = \frac{98 + 99}{2} = 98.5\)

Step 5 ：So, the solutions are: \(\boxed{Q2 = 90}\), \(\boxed{Q1 = 86}\), \(\boxed{Q3 = 98.5}\)