Tables & Graphs Interpretation

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Quick recall

• Read the title, axis labels, units, and scale before calculating.
• For percentage change, divide by the earlier value.

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Formula Cards

1. Percentage share

$$\text{Share (\%)}=\frac{\text{Part}}{\text{Total}}\times100$$

2. Pie-chart angle

$$\theta=\frac{\text{Part}}{\text{Total}}\times360^\circ$$

3. Reading checklist

Check axis labels, units, and scale first. Watch for values in thousands or millions. Compare absolute values or relative shares according to the question.

Worked Examples

Example 1

Question: A total is 200 and one part is 50. Find the percentage share.

Step 1: Divide part by total.

$$\frac{50}{200}=\frac{1}{4}$$

Step 2: Convert to percentage.

$$\frac{1}{4}\times100=25\%$$

Answer: 25%.

Example 2

Question: Product A occupies 90° of a pie chart. Find its share of total sales.

Step 1: Divide by the full circle.

$$\frac{90}{360}=\frac{1}{4}$$

Step 2: Convert to percentage.

$$\frac{1}{4}\times100=25\%$$

Answer: 25%.

Example 3

Question: Sales rise from 40 in January to 60 in February. Find the percentage increase.

Step 1: Find the increase.

$$60-40=20$$

Step 2: Divide by January's value.

$$\frac{20}{40}\times100=50\%$$

Answer: 50% increase.

Drill

Try each question before opening its answer.

Question 1

Pie chart sector is 120°. What % of total?

• Show answer

  33.33%

Question 2

Total sales=500, Product X=125. Find % share.

• Show answer

  25%

Question 3

Bar chart: March=80, April=100. % increase?

• Show answer

  25%

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