Challenge 2: CSV Average Score — Possible Solution
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import csv

with open("scores.csv", "r", newline="") as f:
    reader = csv.DictReader(f)
    scores = [int(row["score"]) for row in reader]

average = sum(scores) / len(scores)
print(average)

Output (using the scores.csv from this chapter's own example — Alice 90, Bob 85):
87.5

WHY THIS WORKS AS AN ANSWER
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csv.DictReader(f) reuses this chapter's own DictReader example
directly — each row comes back as a dict keyed by the header row's
column names, so row["score"] reads the score column by name rather
than by numeric position.

int(row["score"]) is the necessary extra step this challenge's own
hint calls out: every value read from a CSV file (via csv.reader or
csv.DictReader) comes back as a plain string, even a column that
looks numeric — "90", not 90. Wrapping it in int() converts it to a
real integer, reusing the int() casting covered back in Course 1,
Chapter 2, before any arithmetic can be done with it correctly.

[int(row["score"]) for row in reader] reuses the list comprehension
pattern from Course 1/Course 2's comprehension chapters to build the
full list of converted scores in one line while iterating the reader.

sum(scores) / len(scores) then reuses the exact same average-of-a-list
pattern as Course 1, Chapter 9's average(*args) solution — summing
every score and dividing by how many there are — just sourced from a
CSV file's column instead of function arguments.