Answer:
28
Step-by-step explanation:
First step is to find the median of the data set.
The median is the middle value of the data arranged in ascending order. If there is not an exact value then it the average of the values either side of the middle.
23 28 28 36 56 60 61 65 70
↑ median
The first quartile [tex]Q_{1}[/tex] is the middle value on the left side of the median.
23 28 28 36
↑
[tex]Q_{1}[/tex] = [tex]\frac{28+28}{2}[/tex] = [tex]\frac{56}{2}[/tex] = 28
