Answer:
Q₃ = 18
Explanation:
The first step is to find the median
The median is the middle value of the data in ascending order.
5, 8, 10, 10, 15, 18, 23
↑ middle value
median = 10
The upper quartile Q₃ is the middle value of the data to the right of the median, that is
15, 18, 23
↑ middle value
Thus Q₃ = 18