Update weighted_average.md

snippets/weighted_average.md

@@ -1,18 +1,18 @@
 ---
 title: weighted_average
-tags: list,intermediate
+tags: math,list,intermediate
 ---
 
 Returns the weighted average of two or more noumbers.
 
-- Use `sum` to sum the products of the numbers by it's weight and to sum the weights.
-- Use `for i in range(len(nums))` to move over every number in the two lists.
+- Use `sum()` to sum the products of the numbers by their weight and to sum the weights.
+- Use `zip()` and a list comprehension to iterate over the pairs of values and weights.
 
 ```py
-def weightedAverage(nums,weights):
-    return sum(nums[i] * weights[i] for i in range(len(nums))) / sum(weights)
+def weighted_average(nums, weights):
+  return sum(x * y for x, y in zip(nums, weights)) / sum(weights)
 ```
 
 ```py
-weightedAverage([1, 2, 3], [0.6,0.2,0.3]) # 1.727272727272727
+weighted_average([1, 2, 3], [0.6,0.2,0.3]) # 1.72727
 ```