Answer:

Step-by-step explanation:
the mean is given by:

In our case this is:

side note: the main difference between sample mean and population mean is in the 'context'. However, the method to calculate them is the same.
By context I mean: if this the items are taken from some larger category for example: the ages of a few 'students' from a 'class'. Here 'students' are the sample from a larger set that is 'class'. The mean of the 'few students' will be called sample mean. In contrast, if we take the mean of the ages of the whole class then this is called population mean. (population mean == mean of the whole set)
In our case we aren't told exactly where these numbers come from, is this the whole set or a sample from it, the lack of context allows us to assume that the mean can either be population mean or sample mean. So we can safely use any symbol
or
.
Area of the entire rectangle 
Solution:
Area of the blue box = length × width

Area of the blue box 
Area of the pink box = length × width

Area of the pink box 
Area of the green box = length × width

Area of the green box 
Area of the orange box = length × width

Area of the orange box = 24
Total area of the rectangle 

Area of the entire rectangle
Choose the one on the very top.