To find the mean of the data set \( 13, 18, 13, 14, 13, 16, 14, 21, 13 \), follow these steps:
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Sum all the numbers: \[ 13 + 18 + 13 + 14 + 13 + 16 + 14 + 21 + 13 = 13 + 18 + 13 + 14 + 13 + 16 + 14 + 21 + 13 = 13 \times 5 + 18 + 14 + 16 + 21 \]
- \( 13 \times 5 = 65 \)
- \( 65 + 18 + 14 + 16 + 21 = 65 + 69 = 134\)
So, the total sum is \( 134 \).
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Count the number of values in the data set: There are \( 9 \) values.
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Calculate the mean: \[ \text{Mean} = \frac{\text{Sum of the values}}{\text{Number of values}} = \frac{134}{9} \approx 14.89 \]
Therefore, the mean of the data set is approximately \( 14.89 \).