Data Interpretation

Data interpretation questions give a table or chart and ask several quick calculations from it. The skills are reading the data accurately, choosing the right base for each percentage, and approximating when the answer options are far apart.

A worked data set

Annual sales of a company's three products (₹ crore):

Typical questions:

• Growth of A from 2023 to 2024: (198 − 165)/165 = 33/165 = 20%. The base is always the earlier year.
• Average sales of B over the four years: (80 + 96 + 120 + 132)/4 = 107.
• Share of C in 2024: 90/420 ≈ 21.43%.
• Change in C from 2022 to 2023: (60 − 72)/72 ≈ −16.67% (a fall).
• Ratio of A to B in 2023: 165 : 120 = 11 : 8.
• Year with the largest percentage growth in total sales: 2022 (+22.31%), compared with +8.49% in 2023 and +21.74% in 2024. Note that 2024 had the largest absolute increase (+75) but not the largest percentage increase.

years = [2021, 2022, 2023, 2024]
sales = {"A": [120, 150, 165, 198], "B": [80, 96, 120, 132], "C": [60, 72, 60, 90]}
total = [sum(col) for col in zip(*sales.values())]
print("totals:", dict(zip(years, total)))
for i in range(1, 4):
    growth = (total[i] - total[i - 1]) / total[i - 1] * 100
    print(f"{years[i]}: total up {total[i] - total[i - 1]:3} = {growth:.2f}%")
print("A's share over four years:", round(sum(sales["A"]) / sum(total) * 100, 2), "%")
cagr = ((total[-1] / total[0]) ** (1 / 3) - 1) * 100
print("average yearly (compound) growth of the total:", round(cagr, 2), "%")

totals: {2021: 260, 2022: 318, 2023: 345, 2024: 420}
2022: total up  58 = 22.31%
2023: total up  27 = 8.49%
2024: total up  75 = 21.74%
A's share over four years: 47.13 %
average yearly (compound) growth of the total: 17.33 %

Strategies

• Read the units and the question twice: "percentage of", "percentage change", "percentage points" and "ratio" are different things. A share rising from 20% to 25% is a rise of 5 percentage points, but of 25 percent.
• Approximate when the options are well separated: 33/165 is clearly about 1/5.
• Use fractions you know: 1/8 = 12.5%, 1/6 ≈ 16.67%, 1/7 ≈ 14.29%, 1/9 ≈ 11.11%, 1/11 ≈ 9.09%.
• Compound growth over several years is not the average of the yearly rates: total sales grew 61.54% over three years, which is about 17.33% per year compounded, not 61.54/3 ≈ 20.5%.

Practice questions

Use the sales table above.