# Math Help - Weighted Averages

1. ## Weighted Averages

Hi,
Ok, if for example i purchased a car. There would be a total cost but if i split the parts off an average would make the engine worth the same amount as a wheel nut. How could i know how much each item actually cost me. I have read that weighted avearges are what i need.
Thanks

2. Originally Posted by benhathaway
Hi,
Ok, if for example i purchased a car. There would be a total cost but if i split the parts off an average would make the engine worth the same amount as a wheel nut. How could i know how much each item actually cost me. I have read that weighted avearges are what i need.
Thanks
This is the formula for weighted averages:

$\overline x _{(i)} = \frac{{\sum\limits_{i = 1}^k {n_i \overline x _i } }}
{{\sum\limits_{i = 1}^k {n_i } }}
$

EDIT: It could just be me... But the question doesn't make much sense to me.