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🟢 GeeksforGeeks — Aptitude Practice (30 Questions)

Fresher Data Analyst — Quantitative & Logical Reasoning​

Every question includes a detailed step-by-step solution. These are GFG-style problems commonly asked in fresher data analyst aptitude rounds.

SECTION A: Percentages & Profit/Loss (Q1–Q8)​

Q1: A number is increased by 20% and then decreased by 20%. What is the net change?​

Let original = 100
After 20% increase: 100 × 1.20 = 120
After 20% decrease: 120 × 0.80 = 96
Net change = 96 - 100 = -4 → Net DECREASE of 4%

Shortcut: a + b + (ab)/100 = 20 + (-20) + (20 × -20)/100
         = 20 - 20 - 4 = -4% ✅

🧠 Trap alert: Students think 20% up then 20% down = zero. It's ALWAYS a net loss. Same percentage up and down = always net loss.

Q2: If 60% of students in a class are boys and 40% are girls, and 30% of boys and 40% of girls passed, what percentage of the class passed?​

Let total = 100
Boys = 60, Girls = 40
Boys passed = 30% of 60 = 18
Girls passed = 40% of 40 = 16
Total passed = 18 + 16 = 34 → 34% ✅

Q3: A shopkeeper marks goods 40% above cost price and gives a 25% discount. Find the profit percentage.​

Let CP = 100
Marked Price = 100 × 1.40 = 140
Selling Price = 140 × 0.75 = 105
Profit = 105 - 100 = 5 → Profit% = 5% ✅

Shortcut: Effective = 40 + (-25) + (40 × -25)/100
        = 40 - 25 - 10 = 5% ✅

Q4: An article is sold at 10% loss. Had it been sold for ₹90 more, there would have been 5% gain. Find the cost price.​

Let CP = x
SP at 10% loss = 0.90x
SP at 5% gain = 1.05x
Difference = 1.05x - 0.90x = 0.15x = ₹90
x = 90/0.15 = ₹600 ✅

Q5: A trader cheats on both buying and selling. He uses 900g while buying (pays for 1kg) and uses 800g while selling (charges for 1kg). Find his profit percentage.​

Actual CP for 1kg goods = (900/1000) × Cost of 1kg = 0.9 × CP
He sells 800g at price of 1000g = gets price for 1kg but gives 800g

Profit% = [(True value obtained - True cost) / True cost] × 100
He buys 900g for price of 1000g, sells 900g as (900/800) = 1.125 kg
Revenue = 1.125 × SP (where SP = CP since no markup)
Actual profit = (1000/800) × (1000/900) - 1 = 1.25 × 1.111 - 1 = 0.3889
Profit% ≈ 38.89% ✅

Q6: The price of sugar rises by 25%. By what percentage must a household reduce consumption so expenditure stays the same?​

Formula: Required reduction = (Increase% / (100 + Increase%)) × 100
= (25 / 125) × 100 = 20% reduction ✅

Verify: Price up 25% → new price = 1.25x
If you buy 20% less → 0.80 of original quantity
Expenditure = 1.25x × 0.80 = 1.0x → Same as before ✅

🧠 Ye formula ratt lo: Reduce by = (increase / (100+increase)) × 100. Very common question.

Q7: A sells a product to B at 20% profit. B sells it to C at 25% profit. If C paid ₹1500, what was A's cost price?​

Let A's CP = x
A → B: SP = 1.20x
B → C: SP = 1.20x × 1.25 = 1.50x = ₹1500
x = 1500/1.50 = ₹1000 ✅

Q8: In a company, 35% of employees are male. 40% of males and 60% of females like working from home. What percentage of the company likes WFH?​

Let total = 100
Males = 35, Females = 65
Males liking WFH = 40% of 35 = 14
Females liking WFH = 60% of 65 = 39
Total = 14 + 39 = 53 → 53% ✅

SECTION B: Ratios, Averages & Mixtures (Q9–Q14)​

Q9: Salaries of A, B, C are in ratio 2:3:5. If C earns ₹12,000 more than A, find each salary.​

Let salaries = 2x, 3x, 5x
C - A = 5x - 2x = 3x = ₹12,000
x = ₹4,000
A = ₹8,000, B = ₹12,000, C = ₹20,000 ✅

Q10: Average age of 5 members is 28. A new member with age 22 joins. New average?​

Total age = 5 × 28 = 140
New total = 140 + 22 = 162
New average = 162 / 6 = 27 ✅

Q11: A batsman's average after 40 innings is 50. After the 41st inning, his average increases by 2. How many runs did he score in the 41st inning?​

Total after 40 = 40 × 50 = 2000
New average = 52
Total after 41 = 41 × 52 = 2132
Runs in 41st = 2132 - 2000 = 132 ✅

🧠 Pattern: Runs = New avg + (Innings - 1) × Increase = 52 + 40 × 2 = 132. Works every time.

Q12: The average of 6 numbers is 30. If one number is removed, the average becomes 29. Find the removed number.​

Total = 6 × 30 = 180
New total = 5 × 29 = 145
Removed number = 180 - 145 = 35 ✅

Q13: In what ratio should two varieties of tea priced at ₹126/kg and ₹135/kg be mixed to get a mixture worth ₹130/kg?​

Using Alligation:
         126          135
           \         /
            130
           /         \
    135-130=5    130-126=4

Ratio = 5:4 (Cheaper : Dearer) ✅

🧠 Alligation rule: Cross-subtract from the mean. Ratio = (Dearer - Mean) : (Mean - Cheaper).

Q14: A, B, C invest ₹20,000, ₹30,000, ₹50,000 respectively. A invests for 12 months, B for 8 months, C for 6 months. How should a profit of ₹50,000 be distributed?​

A's share = 20000 × 12 = 240000
B's share = 30000 × 8  = 240000
C's share = 50000 × 6  = 300000
Total = 780000

A = (240/780) × 50000 = ₹15,385
B = (240/780) × 50000 = ₹15,385
C = (300/780) × 50000 = ₹19,231 ✅

SECTION C: Time & Work, Speed & Distance (Q15–Q20)​

Q15: A can do a job in 20 days. B can do it in 30 days. A works alone for 5 days, then B joins. How many more days to finish?​

A's rate = 1/20 per day
B's rate = 1/30 per day

Work done by A in 5 days = 5/20 = 1/4
Remaining work = 3/4

(A+B) together rate = 1/20 + 1/30 = 5/60 = 1/12 per day
Time for remaining = (3/4) / (1/12) = (3/4) × 12 = 9 days ✅

Q16: 12 workers can build a wall in 18 days. How many workers are needed to build it in 12 days?​

Total work = 12 × 18 = 216 worker-days
Workers needed for 12 days = 216 / 12 = 18 workers ✅

🧠 Work = Workers × Days. Keep total work constant, adjust variables.

Q17: A pipe fills a tank in 6 hours. A leak empties it in 10 hours. With both working, how long to fill the tank?​

Fill rate = 1/6 per hour
Leak rate = -1/10 per hour
Net rate = 1/6 - 1/10 = (5-3)/30 = 2/30 = 1/15 per hour
Time = 15 hours ✅

Q18: A car travels 300 km at 60 km/hr and returns at 40 km/hr. Find the average speed for the entire trip.​

Average speed = 2 × S1 × S2 / (S1 + S2)
             = 2 × 60 × 40 / (60 + 40)
             = 4800 / 100 = 48 km/hr ✅

NOT (60+40)/2 = 50! This is a common trap.

Q19: Two trains 200m and 300m long run in the same direction at 80 km/hr and 50 km/hr. How long to completely pass?​

Same direction → Relative speed = 80 - 50 = 30 km/hr
Convert: 30 × 5/18 = 25/3 m/s
Total distance = 200 + 300 = 500m
Time = 500 / (25/3) = 500 × 3/25 = 60 seconds ✅

Q20: A man rows upstream 10 km in 5 hours and downstream 10 km in 2 hours. Find his speed in still water and stream speed.​

Upstream speed = 10/5 = 2 km/hr
Downstream speed = 10/2 = 5 km/hr

Speed in still water = (Up + Down) / 2 = (2 + 5) / 2 = 3.5 km/hr
Stream speed = (Down - Up) / 2 = (5 - 2) / 2 = 1.5 km/hr ✅

SECTION D: Probability & Combinatorics (Q21–Q25)​

Q21: From a standard deck of 52 cards, what is the probability of drawing either a King or a Spade?​

P(King) = 4/52
P(Spade) = 13/52
P(King AND Spade) = 1/52 (King of Spades)

P(King OR Spade) = 4/52 + 13/52 - 1/52 = 16/52 = 4/13 ✅

🧠 P(A or B) = P(A) + P(B) - P(A and B). We subtract the overlap so we don't count it twice.

Q22: A committee of 3 is to be formed from 5 men and 4 women. How many ways can the committee contain at least 1 woman?​

Total ways (no restriction) = 9C3 = 84
Ways with NO woman (all men) = 5C3 = 10
Ways with at least 1 woman = 84 - 10 = 74 ✅

🧠 "At least 1" = Total - None. Always use the complement approach.

Q23: A bag has 6 red, 4 blue, 5 green balls. Two balls are drawn. Probability both are red?​

P(1st red) = 6/15
P(2nd red | 1st was red) = 5/14
P(both red) = (6/15) × (5/14) = 30/210 = 1/7 ✅

Q24: How many 4-digit numbers can be formed using digits 1,2,3,4,5 with no repetition?​

Position 1: 5 choices
Position 2: 4 remaining
Position 3: 3 remaining
Position 4: 2 remaining
Total = 5 × 4 × 3 × 2 = 120 ✅

This is 5P4 = 5!/(5-4)! = 120

Q25: A coin is tossed 4 times. Probability of getting exactly 2 heads?​

Using binomial: nCr × p^r × (1-p)^(n-r)
4C2 × (0.5)² × (0.5)² = 6 × 0.25 × 0.25 = 6/16 = 3/8 ✅

Enumerate: HHTT, HTHT, HTTH, THHT, THTH, TTHH = 6 ways
Total outcomes = 2⁴ = 16
P = 6/16 = 3/8 ✅

SECTION E: Number Series & Logical Reasoning (Q26–Q30)​

Q26: Find the next term: 2, 6, 12, 20, 30, ?​

Differences: 4, 6, 8, 10 → increasing by 2
Next difference = 12
Answer = 30 + 12 = 42 ✅
Pattern: n(n+1) → 1×2, 2×3, 3×4, 4×5, 5×6, 6×7 = 42

Q27: Find the missing number: 1, 4, 27, 256, ?​

1 = 1^1
4 = 2^2
27 = 3^3
256 = 4^4
Next = 5^5 = 3125 ✅

Q28: 5, 11, 23, 47, 95, ?​

Pattern: ×2 + 1
5×2+1=11, 11×2+1=23, 23×2+1=47, 47×2+1=95, 95×2+1=191 ✅

Q29: A data table shows quarterly revenue: Q1=₹50L, Q2=₹65L, Q3=₹58L, Q4=₹72L. Find (a) total annual revenue, (b) quarter with highest growth, (c) Q2 as percentage of annual.​

(a) Total = 50+65+58+72 = ₹245L ✅

(b) Growth rates:
    Q1→Q2: (65-50)/50 × 100 = 30.0%
    Q2→Q3: (58-65)/65 × 100 = -10.8%
    Q3→Q4: (72-58)/58 × 100 = 24.1%
    Highest growth: Q2 (30.0%) ✅

(c) Q2 as % of annual: 65/245 × 100 = 26.5% ✅

Q30: In a survey of 200 people, 120 like Tea, 80 like Coffee, and 50 like both. How many like (a) at least one drink, (b) only Tea, (c) neither?​

(a) At least one = Tea + Coffee - Both
   = 120 + 80 - 50 = 150 ✅

(b) Only Tea = Tea - Both = 120 - 50 = 70 ✅

(c) Neither = Total - At least one = 200 - 150 = 50 ✅

🧠 Venn Diagram lagao! Set theory problems are always easier with diagrams. Union = A + B - A∩B.