The variance of a set of values is the square of the standard deviation. Given that the standard deviation is $13.1510 \, \text{kg}$, we can calculate the variance using the formula:

$\text{Variance} = (\text{Standard Deviation})^2$

Substituting the given value:

$\text{Variance} = (13.1510)^2 = 173.9451 \, \text{kg}^2$

Thus, the variance of their weights is approximately $173.9451 \, \text{kg}^2$.

Do you want more details or have any questions about this?

Here are some related questions:

1. What is the difference between variance and standard deviation?
2. How is variance useful in data analysis?
3. Can the variance ever be negative?
4. What happens to variance if all data points are increased by the same value?
5. How would we calculate the sample variance for this data set?

Tip: Variance and standard deviation are closely related, but variance is expressed in squared units while standard deviation is in the same units as the data.