Calculate an average value

We all know how to calculate an average value iteratively:

def average(nums):

    result = 0

    for num in nums:
        result += num

    return result/len(nums)

Could you provide a recursive solution? A formula for updating an average value given a new input might be handy:

$$ \bar{x} \leftarrow \frac{x_i + (n-1)\bar{x}}{n} $$

Here, $\bar x$ stands for an average value, $x_i$ is a new supplied value which is used to update the average, and $n$ corresponds to the recursive call number (excluding the initial call to the function).

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Practicing Coding Interview Questions in Python

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Anleitung zur Übung

Provide the base case for the algorithm.
Define the recursive call for updating the average value.

Interaktive Übung

Versuche dich an dieser Übung, indem du diesen Beispielcode vervollständigst.

# Calculate an average value of the sequence of numbers
def average(nums):
  
    # Base case
    if len(nums) == ____:  
        return ____[____]
    
    # Recursive call
    n = len(nums)
    return (____ + ____ * ____) / ____

# Testing the function
print(average([1, 2, 3, 4, 5]))

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