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Missing Data / Logical DI

Introduction

In Missing Data / Logical Data Interpretation (DI) problems some values in a table, chart, or paragraph are intentionally omitted. You must use given totals, ratios, averages or relationships to logically deduce the missing entries. This pattern trains careful reasoning and algebraic setup - skills essential for exam-style DI where parts of the dataset are hidden.

Pattern: Missing Data / Logical DI

Pattern

Key concept: use totals, differences, ratios or averages to form equations that recover missing values.

Typical approaches:

  1. Translate the given table/paragraph into variables for the unknowns.
  2. Write equations from totals, row/column sums, averages or ratio relationships.
  3. Solve the system step-by-step (substitute or eliminate) and check units.
  4. Always perform a final sum or average check to confirm consistency.

Step-by-Step Example

Question

The table below shows quarterly sales (in ₹ lakh) of Products P and Q. One cell is missing.

QuarterProduct PProduct QTotal (P+Q)
Q1403070
Q255-110
Q36045105
Q4455095

Find: The missing value for Product Q in Q2.

Solution

  1. Step 1: Identify knowns and unknown:

    In Q2: Product P = 55 (₹ lakh), Product Q = unknown (call it x), Total (P+Q) = 110.

  2. Step 2: Form the equation from the total:

    P + Q = 110 → 55 + x = 110.

  3. Step 3: Solve for x:

    x = 110 - 55 = ₹55 lakh.

  4. Final Answer:

    ₹55 lakh (Product Q in Q2).

  5. Quick Check:

    Q2 total = 55 + 55 = 110 ✅. Also verify all totals still make sense in context.

Quick Variations

1. A missing column sum when row totals and other columns are known - subtract known column sums from grand total.

2. Missing average or count - use Average = Total ÷ Count to form the missing variable equation.

3. Some cells missing but row/column ratios given - convert ratios into parts, assign variables and solve simultaneous equations.

Trick to Always Use

  • Step 1 → Label every missing value with a variable (x, y, z) and write down all equations you can extract (row sums, column sums, ratios, averages).
  • Step 2 → Use substitution/elimination: reduce the system to a single-variable equation when possible.
  • Step 3 → After solving, plug values back into the original table and perform a full sum/average check to ensure no arithmetic slip.

Summary

Summary

In Missing Data / Logical DI problems:

  • Convert unknown cells into variables immediately.
  • Derive equations from totals, averages, or ratio relationships.
  • Solve systematically (substitute/eliminate) and avoid guessing.
  • Always run a final consistency check (sum of rows/columns, average, or total).

Practice

(1/5)
1.

Quarterly Sales Report (Missing Entry)

The table shows quarterly sales (in ₹ lakh) for Products A and B. One entry is missing. Use the given totals to find the missing data.

QuarterProduct AProduct BTotal (A + B)
Q1354580
Q240-85
Q35060110
Q4454085

Find the missing value for Product B in Q2.

easy
A. ₹45 lakh
B. ₹40 lakh
C. ₹50 lakh
D. ₹55 lakh

Solution

  1. Step 1: Identify knowns:

    Q2 total = 85; Product A in Q2 = 40.

  2. Step 2: Use total formula:

    Product A + Product B = Total → 40 + B = 85.

  3. Step 3: Solve:

    B = 85 - 40 = .

  4. Final Answer:

    ₹45 lakh → Option A.

  5. Quick Check:

    40 + 45 = 85 ✅

Hint: Subtract the known product value from the total to get the missing one.
Common Mistakes: Adding instead of subtracting when solving for the missing value.
2.

Employee Distribution (One Department Missing)

A company's workforce is divided into three departments: HR, Sales, and Tech. The table shows headcounts, but one value is missing.

DepartmentEmployees
HR40
Sales-
Tech100
Total180

Find the number of employees in Sales.

easy
A. 40
B. 35
C. 50
D. 60

Solution

  1. Step 1: Build equation from total:

    HR + Sales + Tech = Total → 40 + Sales + 100 = 180.

  2. Step 2: Solve for Sales:

    Sales = 180 - (40 + 100) = 180 - 140 = .

  3. Final Answer:

    40 → Option A.

  4. Quick Check:

    40 + 40 + 100 = 180 ✅

Hint: Subtract the sum of known department counts from the total to get the missing department.
Common Mistakes: Forgetting to include all known departments when subtracting from the total.
3.

College Attendance Data (Missing Average)

A college recorded monthly average attendance (in %) for four months. The overall average attendance for all months was 75%. Three months' data are known as shown below.

MonthAttendance %
January70
February80
March-
April75

Find the missing March attendance percentage.

easy
A. 72%
B. 75%
C. 74%
D. 78%

Solution

  1. Step 1: Use average formula:

    (January + February + March + April) ÷ 4 = 75 → (70 + 80 + x + 75) ÷ 4 = 75.

  2. Step 2: Solve for x:

    70 + 80 + x + 75 = 300 → 225 + x = 300 → x = 75.

  3. Final Answer:

    → Option B.

  4. Quick Check:

    (70 + 80 + 75 + 75) ÷ 4 = 300 ÷ 4 = 75 ✅

Hint: Multiply the overall average by the count to get the total, then subtract known months.
Common Mistakes: Forgetting to multiply average by the number of months before subtracting known values.
4.

Production Summary (Missing Yearly Output)

A factory’s total 3-year production was 7,200 units. The table shows production for 2021 and 2022. Find missing 2023 production.

YearProduction (units)
20212,100
20222,300
2023-
Total7,200

Find the production in 2023.

medium
A. 2,700
B. 2,800
C. 2,900
D. 3,000

Solution

  1. Step 1: Sum known years:

    2021 + 2022 = 2,100 + 2,300 = 4,400 units.

  2. Step 2: Subtract from total:

    2023 = Total - (2021 + 2022) = 7,200 - 4,400 = units.

  3. Final Answer:

    2,800 → Option B.

  4. Quick Check:

    2,100 + 2,300 + 2,800 = 7,200 ✅

Hint: Use Total - Sum(known entries) to find the missing year's output.
Common Mistakes: Adding totals instead of subtracting known values from the grand total.
5.

Regional Sales Distribution (Logic-Based Missing Value)

A company’s sales data (₹ lakh) for four regions are given below. The East region’s sales are equal to the average of North and South. The total for all regions is ₹500 lakh. Find the sales for the East region.

RegionSales (₹ lakh)
North120
South160
East-
West80
Total500
medium
A. 120
B. 150
C. 160
D. 140

Solution

  1. Step 1: Compute East from average rule:

    East = (North + South) ÷ 2 = (120 + 160) ÷ 2 = 280 ÷ 2 = .

  2. Step 2: Verify with total:

    Check sum: 120 + 160 + 140 + 80 = 500 → matches the given total, so East = 140 is consistent.

  3. Final Answer:

    140 → Option D.

  4. Quick Check:

    Average(120,160)=140 and total sum = 500 ✅

Hint: Compute the average first, then confirm that all region totals sum to the grand total.
Common Mistakes: Using the grand total without checking that the average condition is satisfied.

Mock Test

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