DI — Mixed & Multiple-Source Graphs

Mixed DI gives two or more linked data sources — e.g. a table + a pie, or a bar chart + a line graph — and the questions force you to combine them. This is where CAT hides its toughest DI, because the answer needs a value from source A plugged into source B. Common in the ~22-question DILR block.

Why "multiple-source" is a difficulty spike

No single chart holds the answer; you must find the linking key (a shared category, a common total, a percentage that unlocks an absolute). Miss the link and the set feels unsolvable.

The linking patterns

Combo	Typical link
Pie (%) + given total	% × total → absolutes to use elsewhere
Table + bar	One provides base, the other a rate/share
Two charts, shared categories	Match category across both to combine
Growth chart + level chart	Apply % change to an absolute level

Method

1. Map both sources: what does each provide (absolutes, %, rates)?
2. Identify the bridge — the quantity common to both.
3. Convert everything into one common unit (usually absolutes) before combining.
4. Solve, reusing intermediate values across the set's questions.

Exam Tricks & Tips

• 🎯 Find the bridge first. Circle the shared category/total that lets you move a number from one source to the other.
• 🎯 Convert to absolutes before combining. Percentages from a pie can't be used with a bar's raw values until you multiply by the total.
• 🎯 A percentage in source A × a base in source B is the archetypal mixed-DI step — expect it.
• 🎯 Keep an intermediate results table. Values you derive early usually feed later questions in the same set.
• 🎯 Watch mismatched units/years across sources — combine only like with like.
• ❌ Common mistake: answering from one chart when the question secretly needs both — always ask "does this need a number from the other source?".

Expected exam pattern

0–2 mixed sets in DILR, often the section's hardest, 3–4 questions each. You'll shuttle between a pie and a total, or a table and a chart. MCQ + TITA. Reward: whoever spots the linking key fast and works in a consistent unit.

Quick recap

Two sources, one answer: map what each gives, find the bridge quantity, convert to a common unit (usually absolutes), then combine. The hallmark step is "% from one source × base from the other". Reuse intermediate values across the set.

Cover the answer, recall, then check. 12 cards on mixed/multi-source DI.

Q1. What defines a mixed-DI set?
A1. Two or more linked data sources (e.g. table + pie) whose questions require combining them.

Q2. Why is it a difficulty spike?
A2. No single chart holds the answer — you must find the linking key between sources.

Q3. What is "the bridge"?
A3. The quantity common to both sources that lets you move a number between them.

Q4. Before combining, what must you do to percentages?
A4. Convert to absolutes (multiply by the relevant total) — a common unit.

Q5. The archetypal mixed-DI step?
A5. A percentage from one source × a base value from the other source.

Q6. How do you combine a pie (%) with a bar (raw values)?
A6. Turn the pie's % into absolutes using its total, then combine like units.

Q7. Why keep an intermediate-results table?
A7. Early-derived values usually feed later questions in the same set.

Q8. What must match before you combine two sources?
A8. Units and time periods — combine only like with like.

Q9. First step when you open a mixed set?
A9. Map what each source provides (absolutes, %, rates).

Q10. The classic mixed-DI mistake?
A10. Answering from one chart when the question secretly needs both.

Q11. How do you apply a growth chart to a level chart?
A11. Apply the % change to the absolute level from the other chart.

Q12. How hard are mixed sets relative to others?
A12. Often the hardest in DILR — linking-key dependent.

Modern CAT DI rarely gives one clean chart. It gives a table plus a pie, or a bar chart plus a caselet, and the answer requires combining them — a value from source 1 feeds a calculation on source 2. These sets punish tunnel vision: students solve using one source and miss that the total, or the split, or the base value lives in the other.

What this tests

Data integration — reading two or more linked representations, identifying which source supplies which piece, and chaining values across them to answer.

The method

Beginner — inventory each source and how they link

Before any question, note what each source gives and what connects them. Typically one source gives totals (a table of annual revenue) and another gives a breakdown (a pie of that revenue's split), sharing a common key (the year, the company). The link is the bridge every question crosses. Find it first.

Intermediate — trace the calculation path across sources

For each question, ask: which source has the number I need, and does it require a value from the other? A question like "revenue from Product X in 2023" might need: total 2023 revenue (from the table) × Product X's share (from the pie). Map the path — source A value → operation → source B value → answer — before calculating. This prevents the classic error of using a percentage as if it were an absolute.

Advanced — the FAST CAT approach: pin the common base, watch for changing bases

• The common base (usually a total) is used repeatedly — compute it once, reuse it.
• Beware shifting bases: a pie for 2022 and a pie for 2023 have different totals; a share that "grew" in % may not have grown in value. Always carry the correct total for each period.
• Some questions need only one source — don't over-fetch. Identify the minimal source set per question.
• When a question combines a rate/percentage (source 1) with an absolute (source 2), set up the expression symbolically, then plug — keeps the two currencies from getting mixed.

Worked example

Source 1 (table): Total sales — 2022 = ₹500 cr, 2023 = ₹600 cr. Source 2 (pies): Product P's share — 2022 = 20%, 2023 = 25%.
Question: By how much did Product P's sales increase from 2022 to 2023?
Cross the sources:

• 2022 P sales = 20% × 500 = ₹100 cr.
• 2023 P sales = 25% × 600 = ₹150 cr.
• Increase = ₹50 cr.
  Answer: ₹50 crore. The trap: reading "share rose 20%→25%" and reporting a 5-percentage-point or "25%" answer. The real increase needs both the changing share and the changing total, chained. Answer: ₹50 crore.

CAT relevance

Multi-source sets are the norm in recent CAT DILR — the section is designed to test integration, not single-chart reading. They're also where careless candidates leak marks by answering from one source. Disciplined source-mapping is what turns a hard-looking combined set into a routine two-step calculation.

Speed tricks & shortcuts

• Inventory both sources and find the linking key before answering.
• Map the calculation path (which source → which value) before computing.
• Compute the common total once, reuse across questions.
• Different periods = different bases — never reuse one total for another year.
• Mnemonic — "Which source, then cross."

Key formulas

• Combine data from multiple charts using a shared quantity (often the total).
• Percentage = part/whole ×100; % change = (new − old)/old ×100.
• Convert pie angles (angle/360×total) to align with bar/line values.
• Ratios link one chart's figure to another's.
• Compute intermediate totals to bridge sources.

Usage: find the quantity common to both charts and use it as the bridge.

Worked Example

Problem: (Two data sources.) A bar chart gives a company's total employees per year; a pie chart gives the 2023 department split.

• Bar: total employees — 2022: 800; 2023: 1000.
• Pie (2023 only): Engineering 40%, Sales 25%, Support 20%, Admin 15%.
  (a) How many people were in Engineering in 2023? (b) If Engineering had 280 people in 2022, what was its percentage growth to 2023? (c) Which single source can, or cannot, answer part (b)?

Solution:
Multiple-source questions require combining two datasets; the key skill is knowing which value comes from which chart and not mixing a percentage from one year with a total from another.

(a) Engineering 2023 = 40% (from the pie, which is 2023-specific) × 1000 (2023 total, from the bar) = 0.40 × 1000 = 400 people.

(b) Engineering growth 2022 → 2023 = (2023 − 2022)/2022 × 100.

• 2023 Engineering = 400 (from part a).
• 2022 Engineering = 280 (given).
  Growth = (400 − 280)/280 × 100 = 120/280 × 100 = 12000/280 ≈ 42.9%.

(c) Neither source ALONE answers (b): the pie is only for 2023, so it gives no 2022 department split; the bar gives only yearly TOTALS, not the Engineering count. You need the pie + bar together (to get 400 for 2023) PLUS the separately given 2022 figure (280). The trap is to apply the 2023 pie percentage (40%) to the 2022 total (800) to get "320" for 2022 Engineering — invalid, because the department mix in 2022 is unknown and need not equal 2023's. Only the explicitly given 280 is legitimate for 2022.

Answer: (a) Engineering 2023 = 40% × 1000 = 400. (b) Growth = (400 − 280)/280 ≈ 42.9%. (c) No single chart suffices: the pie is 2023-only and the bar gives only totals; you must combine them (and use the given 280), never apply the 2023 percentage to the 2022 total.