Sort the data from the smallest one.
42, 55, 69, 74, 78, 83, 83, 97, 99
There are 9 data, n = 9
Find the location of Q₂
Q₂ location = (n + 1)/2
Q₂ location = (9 + 1)/2
Q₂ location = 10/2
Q₂ location = 5
The location of Q₂ is in the fifth order
42 first order
55 second order
69 third order
74 fourth order
78 fifth order
etc
So the Q₂ or the median is 78