Answer:
10.8
Explanation:
You want the average x-value for the following data points: (21, 2), (4, 4), (7, 10), (9, 12), (13,13).
Average
The average is their sum, divided by the number of data points:
mean x = (21 +4 +7 +9 +13)/5 = 54/5 = 10.8
The average value of x is 10.8.
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Additional comment
The average y-value is (2 +4 +10 +12 +13)/5 = 8.2.