PL-300 Visualize and analyze the data Practice Question
You are a Power BI report creator for a non-profit organization. You have a semantic model with a 'Donations' fact table (columns: 'DonationID', 'DonorID', 'Date', 'Amount', 'CampaignID') and a 'Donors' dimension table (columns: 'DonorID', 'DonorName', 'City', 'DonorType' (Individual/Corporate)). You need to create a report page that shows a scatter chart with 'Total Donation Amount' on the X-axis and 'Number of Donations' on the Y-axis, with each point representing a donor type. You also want to add a trend line to show the correlation. When you create the scatter chart, only one point appears (for all donors combined), instead of separate points for Individual and Corporate. What is the most likely cause?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The DonorType field is placed in the 'Values' well instead of the 'Legend' well.
The correct option is B: the DonorType field must be placed in the Legend well so the scatter chart splits into one point per donor type (Individual and Corporate). In Power BI, the Legend well is what creates separate series/points by category, while the Values well holds the numeric measures (Total Donation Amount and Number of Donations). With DonorType in Values, the chart aggregates everything into a single point, which matches the symptom described. Option A is wrong because an inactive relationship would affect filtering/aggregation, not the number of scatter points, and the model already relates Donations to Donors via DonorID. Option C is wrong because SUM and COUNT are appropriate for total amount and donation count, and incorrect aggregation would not by itself collapse categories. Option D is wrong because scatter charts do support multiple categories via the Legend well; small multiples are not required.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The relationship between Donations and Donors is inactive.
Why it's wrong here
In a scatter chart, measures that aggregate across related tables rely on an active relationship for filter propagation from Donors to Donations. If the relationship were inactive, the measures would not return correct aggregates for donor-type slices; instead they would show an error or blank. Since the visual renders points at all, the active relationship is functioning correctly, so this is not the cause.
- ✓
The DonorType field is placed in the 'Values' well instead of the 'Legend' well.
Why this is correct
The Values well in a scatter chart is reserved for numeric measures for the X and Y axes. Dropping DonorType there causes Power BI to treat it as an aggregated value (or a nonsensical measure) rather than as a categorical series selector. To get separate points for each donor type, DonorType must be placed in the Legend well, which creates a distinct series for each category. This misplacement is the exact reason the scatter shows a single cluster instead of separated groups.
- ✗
The measures are incorrectly defined; they should use SUM and COUNT respectively.
Why it's wrong here
The aggregation functions in the measures are appropriate for the scenario: SUM of donation amounts and COUNT of donors are standard and produce correct numbers. If the measures were misdefined, the chart would display incorrect values but would still plot a single series because the category field is absent. The symptom is the lack of distinct series, which is a field-placement issue, not an aggregation issue. Therefore, the measures are not the cause.
- ✗
The scatter chart does not support multiple categories; you need to use a small multiples chart.
Why it's wrong here
The scatter chart in Power BI fully supports multiple categories through the Legend well, which creates separate colored series for each category value. Small multiples are an alternative layout for comparing many categories, but they are not required because the Legend already provides the needed grouping. Placing DonorType in the Legend will produce separate clusters per donor type on the same axes, so the chart's capability is not the limitation. This option incorrectly blames the visual type rather than the field assignment.
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