Calculate a weighted average from a list of values and their corresponding weights.
A regular average gives every value equal weight. A weighted average lets some values count more than others, depending on their importance:
A common example is a grade made up of several parts with different weighting — for example a final exam worth 50%, a project worth 30%, and an oral exam worth 20%. Another example is an investment portfolio where each holding's return is weighted by its share of the total portfolio.
No. The calculator always divides by the sum of the weights you've entered, so the result comes out correctly whether the weights add up to 1, 100, or any other number — as long as they're proportionally correct relative to each other.
A regular (arithmetic) average gives every value equal weight. A weighted average is identical to a regular average only when all the weights are equal — otherwise it gives more influence to the values with a higher weight.
Mathematically, yes, but that rarely makes sense in practice. Most use cases (grades, portfolio shares, surveys) use positive weights that represent a share or an importance.