Answer
$Q_1=Q_2=Q_3=4$
Work Step by Step
We are given the data:
3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5
Determine $Q_2$: there are 14 numbers, $Q_2$ is the average between the 7th and the 8th numbers:
$Q_2=\dfrac{4+4}{2}=4$
Determine $Q_1$: there are 7 numbers on the left of $Q_2$, their median in the 4th number:
$Q_1=4$
Determine $Q_3$: there are 7 numbers on the right of $Q_2$, their median in the 11th number:
$Q_3=4$
We notice that we got:
$Q_1=Q_2=Q_3=4$
