SECTION C: DATA INTERPRETATION
[!IMPORTANT] As a Data Analyst candidate at DecisionTree, Data Interpretation (DI) is the most relevant part of the aptitude round. Expect tables, bar charts, pie charts, or line graphs.
14. Table-Based DI
📝 Example
Table: Quarterly Revenue (₹ lakhs) of 4 Products
| Product | Q1 | Q2 | Q3 | Q4 |
|---|---|---|---|---|
| Alpha | 120 | 150 | 180 | 200 |
| Beta | 90 | 110 | 130 | 160 |
| Gamma | 200 | 180 | 160 | 140 |
| Delta | 60 | 80 | 100 | 120 |
Q1: Which product had the highest annual revenue?
Alpha: 120+150+180+200 = 650
Beta: 90+110+130+160 = 490
Gamma: 200+180+160+140 = 680 ← Highest ✅
Delta: 60+80+100+120 = 360
Q2: What is the % growth of Delta from Q1 to Q4?
Growth = [(120-60)/60] × 100 = 100% ✅
Q3: In Q3, what % of total revenue comes from Alpha?
Total Q3 = 180+130+160+100 = 570
Alpha's share = (180/570) × 100 = 31.58% ✅
Q4: Which product shows a declining trend?
Gamma: 200 → 180 → 160 → 140 (consistently declining) ✅
15. Pie Chart DI
📝 Example
Monthly Expenses of a Company (Total: ₹50 lakhs)
| Category | Percentage |
|---|---|
| Salaries | 40% |
| Rent | 15% |
| Marketing | 20% |
| Technology | 15% |
| Miscellaneous | 10% |
Q1: How much is spent on Marketing?
20% of 50 lakhs = ₹10 lakhs ✅
Q2: If Salaries increase by 10% and total budget stays same, what's the new marketing budget (assuming cut comes from marketing)?
Original salary = 40% of 50L = ₹20L
New salary = 20L × 1.10 = ₹22L
Increase = ₹2L → cut from marketing
New marketing = 10L - 2L = ₹8L ✅
16. Speed Tricks for the Exam
Multiplication Shortcuts
| Multiply by | Trick |
|---|---|
| 5 | Divide by 2, multiply by 10. Ex: 48×5 = 24×10 = 240 |
| 25 | Divide by 4, multiply by 100. Ex: 36×25 = 9×100 = 900 |
| 11 | Write first digit, add consecutive pairs, write last digit. Ex: 34×11 = 3(3+4)4 = 374 |
| 9 | Multiply by 10, subtract original. Ex: 43×9 = 430-43 = 387 |
Percentage Shortcuts
| Percentage | Shortcut |
|---|---|
| 10% | Move decimal one place left |
| 5% | Half of 10% |
| 1% | Move decimal two places left |
| 15% | 10% + 5% |
| 33.33% | Divide by 3 |
| 25% | Divide by 4 |
| 12.5% | Divide by 8 |
Practice Set — Full Mock Test (20 Questions, 30 Minutes)
| # | Question | Answer |
|---|---|---|
| 1 | 35% of 800 | 280 |
| 2 | If CP = ₹400, SP = ₹340, Loss%? | 15% |
| 3 | Average of 12, 15, 18, 21, 24? | 18 |
| 4 | A does work in 20 days, B in 30 days. Together? | 12 days |
| 5 | Train at 72 km/hr. Speed in m/s? | 20 m/s |
| 6 | P(drawing an ace from 52 cards)? | 1/13 |
| 7 | Next in series: 5, 11, 23, 47, ? | 95 (×2+1) |
| 8 | 8C3 = ? | 56 |
| 9 | Divide ₹3,600 in ratio 2:3:4 | ₹800, ₹1200, ₹1600 |
| 10 | A is 25% more than B. B is what % less than A? | 20% |
| 11 | 2 coins tossed, P(at least 1 tail)? | 3/4 |
| 12 | Next in: 1, 4, 9, 16, 25, ? | 36 (perfect squares) |
| 13 | CP = ₹500, MP = ₹700, Discount 20%. Profit%? | 12% (SP=560) |
| 14 | Speed 60 km/hr for 2 hrs, 40 km/hr for 3 hrs. Avg speed? | 48 km/hr |
| 15 | All cats are animals. Some animals are dogs. Some cats are dogs? | Does not follow |
| 16 | A's father's wife's daughter is B. B is A's? | Sister |
| 17 | 5! = ? | 120 |
| 18 | If sum of 7 numbers is 287, average? | 41 |
| 19 | 12.5% of 640? | 80 |
| 20 | Successive discounts of 20% and 10% on ₹1000? | ₹720 |
✅ PRACTICE SET — DETAILED SOLUTIONS WITH THOUGHT PROCESS
🧠 Har question ke saath bataya hai — "Pehle kya socho?" aur "Shortcut kya hai?"
Q1: 35% of 800
🧠 Socho: 35% = 30% + 5%. 10% of 800 = 80. So 30% = 240, 5% = 40. Total = 280.
Shortcut: 10% = 80 → 30% = 240, 5% = 40
Answer = 240 + 40 = 280 ✅
Q2: CP = ₹400, SP = ₹340. Loss%?
🧠 Socho: SP < CP → Loss hai. Formula: Loss% = (Loss/CP) × 100.
Loss = 400 - 340 = ₹60
Loss% = (60/400) × 100 = 15% ✅
💡 Quick check: 60 out of 400 = 6 out of 40 = 15 out of 100 = 15%. Dimag mein fraction simplify karo.
Q3: Average of 12, 15, 18, 21, 24?
🧠 Socho: Yeh arithmetic progression hai (difference = 3). AP mein average = middle term!
Numbers are 5, evenly spaced → Average = middle number = 18 ✅
Verify: (12+15+18+21+24)/5 = 90/5 = 18 ✅
💡 Shortcut yaad rakho: Equally spaced numbers mein average ALWAYS = middle value. Jod-ghataav ki zaroorat nahi!
Q4: A does work in 20 days, B in 30 days. Together?
🧠 Socho: Seedha formula lagao: Together = (a×b)/(a+b)
= (20 × 30) / (20 + 30) = 600 / 50 = 12 days ✅
💡 Trick: Agar numbers chhote hain toh LCM method use karo — LCM(20,30) = 60 units of work. A = 3 units/day, B = 2 units/day. Together = 5 units/day. Time = 60/5 = 12 days.
Q5: Train at 72 km/hr. Speed in m/s?
🧠 Socho: km/hr → m/s = multiply by 5/18. Bas yaad rakho: 5/18.
72 × 5/18 = 72/18 × 5 = 4 × 5 = 20 m/s ✅
💡 Reverse: m/s → km/hr = multiply by 18/5. Example: 20 × 18/5 = 72 km/hr.
Q6: P(drawing an ace from 52 cards)?
🧠 Socho: Deck mein 4 Aces hain (one per suit). Total 52 cards.
P(Ace) = Favorable/Total = 4/52 = 1/13 ✅
💡 Cards ke basic facts yaad karo — interview mein zaroor poochte hain:
- 52 cards, 4 suits (♠♥♦♣), 13 cards per suit
- 4 Aces, 4 Kings, 4 Queens, 4 Jacks
- 26 Red (♥♦), 26 Black (♠♣)
- Face cards = 12 (4 Kings + 4 Queens + 4 Jacks)
Q7: Next in series: 5, 11, 23, 47, ?
🧠 Socho: Pehle differences dekho: 6, 12, 24 → double ho raha hai! Toh next diff = 48. But wait — ek aur pattern check karo: 5×2+1=11, 11×2+1=23, 23×2+1=47, 47×2+1=95
Pattern: ×2 + 1
5 → 5×2+1 = 11
11 → 11×2+1 = 23
23 → 23×2+1 = 47
47 → 47×2+1 = 95 ✅
💡 Elimination trick: Options mein se 95 aur 94 dono ho sakte hain. "×2+1" pattern confirm karne ke liye puri series verify karo.
Q8: 8C3 = ?
🧠 Socho: Combination = n! / (r! × (n-r)!) but shortcut: numerator mein top 3 numbers multiply karo, denominator mein 3! = 6.
8C3 = (8 × 7 × 6) / (3 × 2 × 1) = 336 / 6 = 56 ✅
💡 Shortcut: nCr mein numerator = n se start karke r numbers neeche giro, denominator = r!. Sirf multiply aur divide karo — factorial puri likhne ki zaroorat nahi.
Q9: Divide ₹3,600 in ratio 2:3:4
🧠 Socho: Total parts = 2+3+4 = 9. Each part = 3600/9 = 400.
Total parts = 2 + 3 + 4 = 9
One part = 3600 ÷ 9 = ₹400
Share 1 = 2 × 400 = ₹800
Share 2 = 3 × 400 = ₹1,200
Share 3 = 4 × 400 = ₹1,600 ✅
Verify: 800 + 1200 + 1600 = 3600 ✅
Q10: A is 25% more than B. B is what % less than A?
🧠 Socho: TRAP QUESTION! Bahut log "25%" bol dete hain — GALAT! Base alag hai!
Let B = 100 → A = 125 (25% more)
Ab poochha: B, A se kitna % LESS hai?
Difference = 125 - 100 = 25
Base = A = 125 (kyunki "A se" poocha hai)
B is less than A by = (25/125) × 100 = 20% ✅
💡 Yaad rakho: "X% more" ka reverse "X% less" KABHI nahi hota! Base change ho jaata hai. Hamesha socho: "KISKE comparison mein?"
Q11: 2 coins tossed, P(at least 1 tail)?
🧠 Socho: "At least 1" ka easiest method = 1 - P(none).
Total outcomes = HH, HT, TH, TT = 4
P(NO tails) = P(HH) = 1/4
P(at least 1 tail) = 1 - 1/4 = 3/4 ✅
💡 Golden Rule: "At least 1" = 1 - P(zero). Yeh shortcut HAMESHA use karo — seedha count karne se galti hoti hai.
Q12: Next in: 1, 4, 9, 16, 25, ?
🧠 Socho: Pehle 5 perfect squares hain: 1², 2², 3², 4², 5². Next = 6².
1² = 1
2² = 4
3² = 9
4² = 16
5² = 25
6² = 36 ✅
💡 Agar squares nahi pehchaan paaye toh: Differences dekho: 3, 5, 7, 9 → odd numbers sequentially badh rahe hain → next diff = 11 → 25+11 = 36. Dono methods same answer dete hain.
Q13: CP = ₹500, MP = ₹700, Discount 20%. Profit%?
🧠 Socho: Step by step — pehle SP nikalo (MP se discount lagao), phir profit% nikalo (SP vs CP).
Step 1: SP = MP × (1 - Discount/100) = 700 × 0.80 = ₹560
Step 2: Profit = SP - CP = 560 - 500 = ₹60
Step 3: Profit% = (60/500) × 100 = 12% ✅
💡 Common mistake: Log MP ko CP samajh lete hain. Yaad rakho: MP = Marked Price (jo likha hai), CP = Cost Price (jo actual mein laga), SP = Selling Price (jis pe becha).
Q14: Speed 60 km/hr for 2 hrs, 40 km/hr for 3 hrs. Avg speed?
🧠 Socho: Yeh SAME DISTANCE wala case NAHI hai — time diya hai, distance nahi. Toh seedha formula: Total Distance / Total Time.
Distance 1 = 60 × 2 = 120 km
Distance 2 = 40 × 3 = 120 km
Total Distance = 120 + 120 = 240 km
Total Time = 2 + 3 = 5 hrs
Average Speed = 240/5 = 48 km/hr ✅
💡 Trap pehchaano: Agar SAME DISTANCE par different speeds hain toh harmonic mean lagta hai: 2ab/(a+b). But agar TIME diya hai toh seedha total distance ÷ total time karo. Pehle identify karo: same distance hai ya same time?
Q15: All cats are animals. Some animals are dogs. Conclusion: Some cats are dogs?
🧠 Socho: Venn Diagram banao. Cats ka circle Animals ke andar hai. Dogs ka circle Animals se overlap karta hai. But dogs waala overlap "Animals minus Cats" waale area mein bhi ho sakta hai!
Cats ⊂ Animals
Dogs ∩ Animals ≠ ∅ (some overlap)
But: Dogs ka overlap Cats ke saath ZARURI nahi hai.
Conclusion: DOES NOT FOLLOW ✅
💡 Syllogism ka #1 rule: "Some A are B" + "All B are C" → "Some A are C" follow karta hai. But "All A are B" + "Some B are C" → "Some A are C" FOLLOW NAHI KARTA. "Some" waala portion B ke non-A part mein ho sakta hai.
Q16: A's father's wife's daughter is B. B is A's?
🧠 Socho: Step by step relationship todho.
A's father → papa
A's father's wife → papa ki biwi → mummy (ya step-mother)
A's father's wife's daughter → mummy ki beti → A ki SISTER (ya step-sister)
Answer: B is A's SISTER ✅
💡 Blood relation tip: Jab complex lag rahi ho, toh ek ek step mein todho aur family tree banao paper pe. Dimag mein mat karo!
Q17: 5! = ?
🧠 Socho: 5! = 5 × 4 × 3 × 2 × 1 = 120. Yeh ratt lo — bahut baar aata hai.
5! = 5 × 4 × 3 × 2 × 1 = 120 ✅
💡 Common factorials yaad rakho: 0! = 1, 1! = 1, 2! = 2, 3! = 6, 4! = 24, 5! = 120, 6! = 720, 7! = 5040
Q18: Sum of 7 numbers is 287. Average?
🧠 Socho: Average = Sum / Count. Bas itna hi hai!
Average = 287 / 7 = 41 ✅
💡 Quick division trick: 287 ÷ 7 → 7 × 40 = 280, 287-280 = 7, 7÷7 = 1. So answer = 40+1 = 41.
Q19: 12.5% of 640?
🧠 Socho: 12.5% = 1/8. Toh 640 ÷ 8 karo. DONE!
12.5% = 1/8
640 ÷ 8 = 80 ✅
💡 Yeh percentage-fraction conversions zaroor yaad karo: 12.5% = 1/8, 25% = 1/4, 33.33% = 1/3, 50% = 1/2, 66.67% = 2/3, 75% = 3/4
Q20: Successive discounts of 20% and 10% on ₹1000?
🧠 Socho: Successive = ek ke baad doosra. Pehle 20% discount lagao, phir uss NAYE price pe 10% lagao. DO NOT add 20+10=30%!
Step 1: After 20% discount = 1000 × (1 - 0.20) = 1000 × 0.80 = ₹800
Step 2: After 10% discount on ₹800 = 800 × (1 - 0.10) = 800 × 0.90 = ₹720 ✅
💡 Formula shortcut: Successive discounts a% and b% → Final price = Original × (1-a/100) × (1-b/100) = 1000 × 0.8 × 0.9 = ₹720.
⚠️ TRAP: 20% + 10% ≠ 30% discount! Actual discount = 1000-720 = 280, so effective discount = 28%, NOT 30%. Formula for effective discount = a + b - (a×b)/100 = 20 + 10 - (200/100) = 28%.
Preparation Tip: Roz 20–30 problems practice karo 2 hafte tak. Apps: IndiaBIX, PrepInsta, Testbook. Speed aur accuracy DONO chahiye — target 85%+ accuracy, 1–1.5 min per question. Timer lagake practice karo!