Data Analytics Course Test

Which keyword is used to define a function in Python?

Deselect Answer

fun

function

define

def

Which operation does np.dot(A, B) perform?

Deselect Answer

Matrix multiplication

Transpose

Summation

Element-wise multiplication

Which method writes a DataFrame to Excel?

Deselect Answer

df.write_excel()

df.to_csv()

df.to_excel()

df.save_excel()

Which of the following creates an array of zeros in NumPy?

Deselect Answer

np.zeros()

np.ones()

np.array(0)

np.empty()

Which of the following is NOT a visualization in Power BI?

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Heatmap

TreeMap

Matrix

Bar chart

Which method sorts values in Pandas DataFrame?

Deselect Answer

Both a and b

df.sort_index()

df.sort_values()

None

What is the shape of np.array([[1,2,3],[4,5,6]])?

Deselect Answer

(3,2)

(2,3)

(1,6)

(6,1)

Which function is used to merge two DataFrames?

Deselect Answer

All of the above

pd.merge()

pd.join()

pd.concat()

Which of the following is mutable in Python?

Deselect Answer

List

Integer

String

Tuple

Which attribute shows the number of rows and columns in Pandas?

Deselect Answer

df.size

df.length

df.dimension

df.shape

Python (Frequency Count) You have a list of numbers with millions of elements. Which method is the most efficient way to find the top 3 most frequent numbers? 5 Marks

Deselect Answer

Use list.count() in a loop

Sort the list and take first 3 values

Use collections.Counter().most_common(3)

Convert to Pandas DataFrame and use value_counts()

Which of the following SQL queries retrieves all students with marks greater than 80?

Deselect Answer

SELECT students WHERE marks > 80;

SELECT * FROM students GROUP BY marks > 80;

SELECT * FROM students HAVING marks > 80;

SELECT * FROM students WHERE marks > 80;

Power BI (YTD vs LYTD) You want to calculate Year-to-Date (YTD) sales compared to last year. Which DAX formula is correct? 5 Marks

Deselect Answer

YTD Sales = SUMX(Sales, Sales[Amount])

YTD Sales = SUM(Sales[Amount])

YTD Sales = TOTALYTD(SUM(Sales[Amount]), Sales[Date]) LYTD Sales = CALCULATE([YTD Sales], SAMEPERIODLASTYEAR(Sales[Date]))

YTD Sales = CALCULATE(SUM(Sales[Amount]), DATEADD(Sales[Date], -12, MONTH))

Which function is used to create pivot tables in Pandas?

Deselect Answer

pd.pivot_table()

Both b and c

df.pivot_table()

df.pivot()

What does df.describe() do?

Deselect Answer

Drops missing values

Describes data types

Shows index info

Summarizes numeric columns

Which SQL clause is used for sorting?

Deselect Answer

SORT BY

HAVING

ORDER BY

GROUP BY

What will df['col1'].unique() return?

Deselect Answer

None

Index of unique rows

Count of unique values

Unique values in column

Which of the following is NOT a data visualization library in Python?

Deselect Answer

ggplot2

Matplotlib

Seaborn

Plotly

Which method gives the first 5 rows of a DataFrame?

Deselect Answer

df.first()

df.top()

df.head()

df.tail()

What does df.isnull().sum() return?

Deselect Answer

Removes null values

Fills null values with 0

Counts null values per column

Deletes null columns

Which of the following is NOT a step in the data analysis process?

Deselect Answer

Data Cleaning

Data Collection

Model Training

Data Degradation

Which data type does range(5) return in Python 3?

Deselect Answer

range object

array

tuple

list

What is the output of len(set([1,2,2,3,3,3]))?

Deselect Answer

1

2

6

3

What will df.iloc[0, 1] return?

Deselect Answer

Value at first row, second column

Value at second row, first column

Value at first row, first column

None of the above

NumPy (Conditional Replacement) You have a 2D NumPy array. You want to replace all negative numbers with 0, but only for rows where the row sum is negative. Which is correct? 5 Marks

Deselect Answer

Use nested for loops

arr[arr < 0] = 0

arr[np.sum(arr, axis=1) < 0] = np.clip(arr, 0, None)

arr[np.sum(arr, axis=1) < 0] = np.where(arr[np.sum(arr, axis=1) < 0] < 0, 0, arr[np.sum(arr, axis=1) < 0])

In Pandas, which function is used to read a CSV file?

Deselect Answer

pd.read()

pd.csv_read()

pd.read_csv()

pd.load_csv()

Which language is used in Power BI for data modeling?

Deselect Answer

SQL

Python

DAX

R

What does len("Data Science") return?

Deselect Answer

12

10

13

11

In Power BI, which type of join is used by default in relationships?

Deselect Answer

Right Join

Inner Join

Left Join

Full Join

What type of data is the number of students in a class?

Deselect Answer

Discrete

Continuous

Ordinal

Categorical

Which function replaces missing values with a given number?

Deselect Answer

df.fillna()

df.dropna()

df.replace()

df.null_replace()

What is the output of bool([])?

Deselect Answer

Error

False

True

None

Which Pandas function is used to combine DataFrames vertically?

Deselect Answer

pd.append()

pd.join()

pd.concat()

pd.merge()

Which of the following is used to handle missing values in Python?

Deselect Answer

dropna()

Both a and b

None of the above

fillna()

In SQL, which clause is used to filter aggregated results?

Deselect Answer

HAVING

ORDER BY

GROUP BY

WHERE

Which of the following is used for exception handling in Python?

Deselect Answer

handle-error

error-resolve

try-except

do-catch

Pandas (Handling Missing Values) You want to replace missing values in some columns with the mean and in others with the mode. Which Pandas approach is most efficient? 5 Marks

Deselect Answer

Use SQL inside Pandas with pd.read_sql()

Use df.fillna(df.mean()) for all columns

Loop through each column with for and apply fillna()

Apply df.apply(lambda x: x.fillna(x.mean()) if x.dtype!='object' else x.fillna(x.mode()[0]))

Which of the following is not a Python data structure?

Deselect Answer

Dictionary

List

Set

Stack

What will print(type(lambda x: x+1)) return?

Deselect Answer

Error

What is the output of list("data")?

Deselect Answer

['da','ta']

Error

['data']

['d','a','t','a']

Which of the following is NOT a Power BI component?

Deselect Answer

Power Query

Power View

Power Pivot

Power Join

Which module in Python is used for regular expressions?

Deselect Answer

string

re

regex

pattern

SQL (Top N per Group) You need the top 3 customers by total sales in each region. Which SQL query is correct? 5 Marks

Deselect Answer

SELECT region, customer_id, SUM(amount) AS total_sales FROM Sales s JOIN Customers c ON s.customer_id = c.customer_id GROUP BY region, customer_id ORDER BY region, total_sales DESC LIMIT 3;

None of the above

SELECT region, customer_id, total_sales FROM ( SELECT c.region, s.customer_id, SUM(s.amount) AS total_sales, ROW_NUMBER() OVER(PARTITION BY c.region ORDER BY SUM(s.amount) DESC) AS rnk FROM Sales s JOIN Customers c ON s.customer_id = c.customer_id GROUP BY c.region, s.customer_id ) t WHERE rnk <= 3;

SELECT TOP 3 region, customer_id, SUM(amount) FROM Sales GROUP BY region, customer_id;

Which SQL keyword is used to remove duplicate values from a result set?

Deselect Answer

UNIQUE

GROUP BY

DISTINCT

HAVING

What is the output of sorted([3,1,2])?

Deselect Answer

[1,2,3]

Error

[3,2,1]

None

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