Question bank

Pick an answer to see if you're right — with an explanation.

All topics Python SQL / MySQL Data Science NumPy Pandas Matplotlib Machine Learning Deep Learning Artificial Intelligence Large Language Models Django APIs Git & GitHub Power BI Excel Statistics

Git & GitHubHard

What does `git bisect run` use to decide whether each commit is good or bad?

git bisect start HEAD v2.1.0
git bisect run python manage.py test billing

aThe commit message

bWhether the files changed

cThe exit code of the command: 0 is good, non-zero is bad

dThe author of the commit

Large Language ModelsHard

When is fine-tuning the most justified choice?

aTo teach the model this morning's stock levels

bBefore trying any prompt changes

cWhen evaluations show prompting and RAG cannot achieve a required consistent format or narrow skill at scale

dTo stop prompt injection completely

Machine LearningHard

You `joblib.dump` a fitted pipeline with scikit-learn 1.5 and load it in production. What is the safest practice?

aLoad it with any newer scikit-learn version

bConvert it to CSV first

cPin the same library versions in production and only load files from trusted sources

dRe-fit the pipeline on each request

MatplotlibHard

You plot daily sales where the date column holds strings like '05-04-2025'. Ticks are crowded and the spacing ignores missing days. What is the best fix?

aRotate the labels 90 degrees

bConvert with pd.to_datetime(col, dayfirst=True) and sort before plotting

cUse a bar chart instead

dSet plt.xticks([]) to hide labels

NumPyHard

After `v = a.reshape(2, 6)` on a contiguous 12-element array `a`, you run `v[0, 0] = 99`. What happens to `a[0]`?

aIt stays unchanged because reshape copies

bIt raises an error because views are read-only

cIt becomes NaN

dIt also becomes 99 because v is a view sharing memory

PandasHard

Which statement about `df[df['city'] == 'Pune']['amount'] = 0` is correct?

aIt reliably sets Pune amounts to 0

bIt raises a SyntaxError

cIt deletes Pune rows

dIt may modify a temporary copy, leaving df unchanged; use df.loc[mask, 'amount'] = 0

Power BIHard

On 12 September, `Total Sales` covers 12 days but `SAMEPERIODLASTYEAR` returns all 30 days of last September, making YoY look awful. What is the correct fix?

aRestrict the prior-year measure to the same number of elapsed days, e.g. by adding a filter up to EDATE(MAX(Sales[InvoiceDate]), -12)

bReplace SAMEPERIODLASTYEAR with PREVIOUSYEAR

cSet the date table's end date to today so future days disappear

dChange the relationship to bi-directional so filters flow back to the date table

PythonHard

What does this print?

def add(item, bucket=[]):
    bucket.append(item)
    return bucket
add(1)
print(add(2))

a[2]

b[1, 2]

c[1]

d[]

SQL / MySQLHard

With `SUM(revenue) OVER (PARTITION BY branch ORDER BY month)` and no explicit frame, what is computed?

aTotal revenue of the branch on every row

bRevenue of the current month only

cA running total from the branch's first month up to the current month

dTotal revenue across all branches

StatisticsHard

A test planned a 50/50 split but recorded 51,800 vs 48,200 users. What should you do first?

aInvestigate a sample ratio mismatch before trusting any result

bDeclare the larger group the winner

cReweight the results and continue

dIgnore it; splits never match exactly