For this question, any non-integer answers should be entered as decimals, rounded to the hundredths place. Consider this data set. 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 The mean of the data set is , and the sample proportion of numbers less than the mean is .

Answer:
The mean of the data set is 22.1 , and the sample proportion of numbers less than the mean is 0.53

Explanation:
.
1) Mean

Formula: mean = sum of values / number of data

sum of values = 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

number of data = 15

mean = 331.5 / 15 = 22.10

2) proportion of numbers less than the mean

This is easier if you order the data. These are the data in growing order:

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 discontinues line shows the split of the data that are less than the mean.

Those are 8 numbers less than 22.1 and the proportion is:

8 / 15 = 0.53