Data Interpretation • Topic 4 of 4

Multi-Source Data Sets

The hardest Data Interpretation sets give you two or more linked displays — say a table beside a bar graph, or a pie plus a line chart — and each question forces you to pull a number from one and a number from the other. The skill is cross-referencing: read what each display holds and how they connect (often a shared total or a shared category), then plan the two-step path before you calculate. A frequent structure gives totals in one figure and percentage breakdowns in another, so you multiply a percent from chart B by a total from chart A. Keep your units aligned across sources — one display might be in thousands and the other in raw counts. Because these questions chain operations, a small rounding slip early can push you to the wrong answer choice; when the choices are close, carry exact figures, and when they are far apart, estimate boldly and move on. Do not compute figures the question never asks for — multi-source displays deliberately include extra data as bait.

Two linked displays: a bar chart of quarterly totals beside a pie chart of the regional splitQuarterly totals ($000s)40556550Q1Q2Q3Q4Revenue by region40%35%25%North 40% · South 35% · West 25%

✅ Solved examples

1. Chart A: total employees = 4,000. Chart B (a pie of employees): Engineering 25%, Sales 30%, Support 20%, Admin 25%. How many work in Sales?
Sales = 30% of 4,000 = 0.30 × 4,000 = 1,200 employees.
2. Using the same charts, Chart C says 60% of Engineering staff hold a graduate degree. How many Engineering staff hold a graduate degree?
Engineering = 25% of 4,000 = 1,000. Graduate holders = 60% of 1,000 = 600.
3. A table gives 2023 total revenue = $50M. A bar graph splits revenue by region: North 40%, South 35%, West 25%. How much more did North earn than West?
North = 0.40 × 50 = $20M; West = 0.25 × 50 = $12.5M. Difference = 20 − 12.5 = $7.5M.
4. Quantitative Comparison. Chart A: City P has 20,000 households; City Q has 30,000. Chart B: 15% of P’s households and 8% of Q’s own an electric car. Quantity A: electric-car households in P. Quantity B: electric-car households in Q. Which is greater?
P: 0.15 × 20,000 = 3,000. Q: 0.08 × 30,000 = 2,400. 3,000 > 2,400, so Quantity A is greater. Both a percent (Chart B) and a total (Chart A) must be combined for each city.

✏️ Practice — try these, take hints as needed

1. Total students = 2,500 (Chart A). Chart B pie: Science 40%. How many study Science?
Multiply percent by total.
0.40 × 2500.
Compute the product.
1,000
2. From the same set, Chart C says 30% of Science students take Physics. How many take Physics?
Science students = 1,000.
0.30 × 1000.
Two chained percents.
300
3. Table: total budget $8M. Bar chart: R&D is 45%. How much funds R&D?
Percent of the total.
0.45 × 8.
In millions of dollars.
$3.6M
4. City A has 10,000 homes, 12% with solar. City B has 8,000 homes, 20% with solar. Which city has more solar homes?
Convert each to a count.
A: 0.12 × 10000 = 1200.
B: 0.20 × 8000 = 1600.
City B (1,600 vs 1,200)
5. Chart A: 5,000 tickets sold. Chart B: 60% were adult tickets. Chart C: adult tickets cost $20 each. Total adult-ticket revenue?
Adult tickets = 60% of 5,000.
0.60 × 5000 = 3000.
Multiply by $20.
$60,000

📝 Topic test — 8 questions

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