A data analyst is writing a function that takes a list of numbers and returns the median. The function should not modify the input list. Which implementation is correct and efficient?

def median(numbers): sorted_nums = sorted(numbers) n = len(sorted_nums) mid = n // 2 if n % 2 == 0: return (sorted_nums[mid - 1] + sorted_nums[mid]) / 2 else: return sorted_nums[mid]

def median(numbers): numbers.sort() n = len(numbers) mid = n // 2 if n % 2 == 0: return (numbers[mid - 1] + numbers[mid]) / 2 else: return numbers[mid]

def median(numbers): return statistics.median(numbers)

def median(numbers): sorted_nums = numbers[:] sorted_nums.sort() n = len(sorted_nums) mid = n // 2 if n % 2 == 0: return (sorted_nums[mid - 1] + sorted_nums[mid]) / 2 else: return sorted_nums[mid]

A data analyst has a list of customer IDs that may contain duplicates. The analyst needs to produce a list of unique customer IDs in the order they first appear. Which approach is both efficient and preserves the original order?

Use a set to track seen IDs and a list to store unique IDs in order.

Use the sorted() function on the set of IDs.

Use list comprehension with a condition checking if the element is already in the result list.

Convert the list to a set and then back to a list.

A data analyst has a set of customer IDs and a list of orders, each order being a tuple (customer_id, amount). They need to find the total amount spent by customers in the set. Which code snippet is most efficient?

total = 0 for cid, amount in orders: if cid in customer_set: total += amount

total = sum(amount for cid, amount in orders if cid in customer_set)

total = sum(amount for cid, amount in orders if cid in list(customer_set))

total = sum(amount for cid, amount in orders if customer_set.issuperset([cid]))

A data analyst writes a function to clean a list of strings by stripping whitespace and converting to lowercase. The function should modify the list in place and return None. Which implementation is correct?

def clean_list(items): for i in range(len(items)): items[i] = items[i].strip().lower()

def clean_list(items): items = [item.strip().lower() for item in items]

def clean_list(items): return [item.strip().lower() for item in items]

def clean_list(items): for item in items: item = item.strip().lower()

A data analyst is working in a Jupyter notebook and needs to load a CSV file into a pandas DataFrame, then display the first 5 rows. Which code snippet correctly accomplishes this?

import pandas as pd df = pd.read_csv('data.csv') df.head(5).show()

import pandas as pd df = pd.read_csv('data.csv') df.head()

import numpy as np df = np.loadtxt('data.csv', delimiter=',') df.head()

import pandas as pd df = pd.read_csv('data.csv') print(df[:5])

Python InstitutePCAD - Certified Associate in Data Analytics with Python

Domain 2Objective 1

Core Python Proficiency PCAD-31 Practice Questions (Page 9)

Part of the Programming and Database Skills domain, which accounts for 33.3% of the PCAD-31 exam. Python Institute does not publish an official question count, but from its 60-minute exam (~25–40 total, ~8–8 in this domain), expect 2–2 from this objective — we provide 50 practice questions to prepare you well beyond it. (estimate)

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Questions 41–45

41expert · hard
A data analyst is writing a function that takes a list of numbers and returns the median. The function should not modify the input list. Which implementation is correct and efficient?
Select an answer first
42application · medium
A data analyst has a list of customer IDs that may contain duplicates. The analyst needs to produce a list of unique customer IDs in the order they first appear. Which approach is both efficient and preserves the original order?
Select an answer first
43expert · medium
A data analyst has a set of customer IDs and a list of orders, each order being a tuple (customer_id, amount). They need to find the total amount spent by customers in the set. Which code snippet is most efficient?
Select an answer first
44application · medium
A data analyst writes a function to clean a list of strings by stripping whitespace and converting to lowercase. The function should modify the list in place and return None. Which implementation is correct?
Select an answer first
45application · easy
A data analyst is working in a Jupyter notebook and needs to load a CSV file into a pandas DataFrame, then display the first 5 rows. Which code snippet correctly accomplishes this?
Select an answer first

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