Quiz, Python for data

Answer the questions about the course. You pass with 70 percent. When you do not know an answer, look at the lesson again and come back.

Question 1 of 14

What happens to the file when the block of this with statement ends?

with open("notes.txt", encoding="utf-8") as file:
    text = file.read()

Python closes the file.Python deletes the file.Python saves a copy of the file.Python reads the file a second time.

Question 2 of 14

Why do you read a CSV file with the csv module, and not with line.split(",")?

The csv module changes each number from text to a number.A value can have a comma inside quotation marks, and split cuts that value in two.split cannot read more than one line.The csv module is the only tool that can open a file.

Question 3 of 14

A file has the header row trip_id,minutes and the row 1017,52. You read it with csv.DictReader into the list trips. What is trips[0]["minutes"]?

The number 52.The text "52".The text "minutes".The list ["1017", "52"].

Question 4 of 14

Which line makes a list of the trips that took more than 30 minutes?

[trip for trip in trips if trip["minutes"] > 30][trip if trip["minutes"] > 30 for trip in trips][trips for trip["minutes"] > 30]trips["minutes"] > 30

Question 5 of 14

What does this line give?

sorted(trips, key=lambda trip: trip["minutes"], reverse=True)[:3]

The 3 shortest trips, with the shortest trip first.The 3 longest trips, with the longest trip first.The first 3 trips of the file.All trips that took 3 minutes.

Question 6 of 14

This loop counts the trips of each station. Why does it use counts.get(station, 0) and not counts[station]?

counts = {}
for trip in trips:
    station = trip["start"]
    counts[station] = counts.get(station, 0) + 1

get is faster than square brackets.get gives 0 for a station that is not in the dictionary yet. Square brackets stop with a KeyError.get sorts the dictionary.Square brackets work only with numbers as keys.

Question 7 of 14

The times of five trips are [10, 12, 14, 20, 600]. Which statements are true? Choose all that apply.

Choose all answers that apply.

The median is 14.The mean is larger than every value except one.The mean is the best number to describe a usual trip in this list.The value 600 is an outlier.

Question 8 of 14

What does this code print?

def to_number(text):
    try:
        return int(text)
    except ValueError:
        return None


print(to_number("7 km"))

7None7 kmThe program stops with a ValueError.

Question 9 of 14

You remove 5 rows from a file of 14 rows, because their values cannot be true. What do you do with that fact?

Nothing. The result is correct now.You change the source file, so that nobody sees the wrong rows again.You report that you kept 9 of 14 rows, and you say why you removed the others.You put the value 0 into the wrong rows and keep them.

Question 10 of 14

datetime.fromisoformat("2026-06-06T10:20").weekday() gives 5. Which day is it?

ThursdayFridaySaturdaySunday

Question 11 of 14

A trip starts at Ferry Dock, and zone_of has no key with that name. What does zone_of.get(trip["start"], "unknown") give?

The text "unknown".None.An empty text.The program stops with a KeyError.

Question 12 of 14

Which statements about JSON are true? Choose all that apply.

Choose all answers that apply.

A number in a JSON file is a number in Python. You do not convert it.json.load changes true to True, and null to None.A text in JSON can be in single quotation marks.A JSON object in braces becomes a dictionary.

Question 13 of 14

Is "art" in "The start was hard" true or false, and why?

False, because art is not a word of the text.True, because the letters art are inside the word start.False, because the text has no capital A.It stops with an error, because in works only with lists.

Question 14 of 14

Which mode of open adds text to the end of a file and keeps the old content?

"r""w""a""x"

Answer every question to check.