def normalize_weights(weights):
    """Normalises a list of numerical values (weights) into probabilities.

    Every weight in the list is assigned a probability proportional to its
    value divided by the sum of all values.

    Args:
        weights (list): A list of numerical values

    Returns:
        list: A list containing values which sum to 1.
    """
    total = sum(weights)
    return [weight / total for weight in weights]