The mean of the data set is 22.1
The sample proportion of numbers less than the mean is %53
To find the mean,
We would sum the numbers and then divide them by the number of data.
25.5 + 26 + 18.2 + 15.3 + 28.5 + 27 + 20.7 + 20.2 + 26.1 + 18.2 + 21.4 + 17.9 + 24.3 + 22.6 + 19.6
= 331.5
331.5/15= 22.10.
To find the proportion of numbers, we would order them:
15.3
17.9
18.2
18.2
19.6
20.2
20.7
21.4
---------
22.6
24.3
25.5
26
26.1
27
28.5
The discontinuous line shows the split of the data that are less than the mean.
Those data are 8 in number and their proportion is:
8 / 15
= 0.53
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