Line charts in Power BI - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ visualization

intermediate

Identify the best use case for a line chart

Which scenario is most suitable for using a line chart in Power BI?

A Displaying parts of a whole in a snapshot

B Showing sales trends over several months

C Listing customer names alphabetically

D Comparing product categories in a single year

💡 Hint

Think about what line charts are best at showing over time.

Line charts are ideal for showing trends and changes over time, such as monthly sales.

❓ dax_lod_result

intermediate

Calculate cumulative sales for a line chart

Given a Sales table with columns Date and Amount, which DAX measure correctly calculates cumulative sales over time for a line chart?

Power BI

Cumulative Sales = CALCULATE(SUM(Sales[Amount]), FILTER(ALLSELECTED(Sales[Date]), Sales[Date] <= MAX(Sales[Date])))

A Cumulative Sales = CALCULATE(SUM(Sales[Amount]), FILTER(ALLSELECTED(Sales[Date]), Sales[Date] <= MAX(Sales[Date])))

B Cumulative Sales = SUMX(FILTER(Sales, Sales[Date] >= MIN(Sales[Date])), Sales[Amount])

C Cumulative Sales = CALCULATE(SUM(Sales[Amount]), FILTER(Sales, Sales[Date] >= MAX(Sales[Date])))

D Cumulative Sales = SUM(Sales[Amount])

💡 Hint

Look for a measure that sums amounts up to the current date.

Option A correctly sums sales amounts for all dates up to the current date using ALLSELECTED and MAX.

🔧 Formula Fix

advanced

Find the error in this line chart measure

Why does this DAX measure for cumulative sales produce incorrect results in a line chart?

Cumulative Sales = CALCULATE(SUM(Sales[Amount]), FILTER(ALL(Sales[Date]), Sales[Date] <= MAX(Sales[Date])))

Power BI

Cumulative Sales = CALCULATE(SUM(Sales[Amount]), FILTER(ALL(Sales[Date]), Sales[Date] <= MAX(Sales[Date])))

A MAX(Sales[Date]) is invalid inside FILTER and causes a syntax error

B The FILTER condition uses <= instead of <, causing duplicate sums

C SUM should be replaced with SUMX for correct aggregation

D Using ALL removes all filters including slicers, causing the line chart to ignore user selections

💡 Hint

Consider how ALL affects filtering in Power BI visuals.

ALL removes all filters including slicers, so the measure ignores user selections, leading to incorrect cumulative sums.

🧠 Conceptual

advanced

Understanding axis scaling in line charts

What is the effect of setting the Y-axis to 'Logarithmic scale' in a Power BI line chart?

A It changes the X-axis to show dates in a logarithmic scale

B It reverses the order of values on the Y-axis

C It compresses large values and expands small values, making exponential growth easier to see

D It removes all zero and negative values from the chart

💡 Hint

Think about how logarithmic scales transform data visually.

Logarithmic scale compresses large values and expands small values, helping to visualize exponential trends clearly.

🎯 Scenario

expert

Designing a line chart for multiple categories with different scales

You need to create a line chart showing monthly sales for two product categories. One category has sales in thousands, the other in millions. How do you best design the chart to compare trends clearly?

A Use a dual Y-axis line chart, assigning each category to its own Y-axis scale

B Convert all sales to the same unit before plotting on a single Y-axis

C Create two separate line charts side by side, each with its own scale

D Combine both categories on a single Y-axis without scaling, to keep it simple

💡 Hint

Think about how to show different value ranges clearly in one chart.

Dual Y-axis allows comparing trends of categories with different scales in one chart without distortion.