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AQA GCSE · Question 13.2 · Data Visualization and Representation
Look at Table 1 in the Data Sheet.
Use the grid provided to draw a percentage composite bar chart for the two years 2008 and 2018.
Show any calculations you make.
Look at Table 1 in the Data Sheet.
Use the grid provided to draw a percentage composite bar chart for the two years 2008 and 2018.
Show any calculations you make.
How to approach this question
1. For each year (2008 and 2018), calculate the percentage for each certificate category. The formula is (Number for category / Total for year) * 100.
2. For each year, calculate the cumulative percentages. This is the running total you will use to mark the sections on the bar.
3. Draw two bars, one for 2008 and one for 2018. Both bars must go up to 100% on the y-axis.
4. Divide each bar into segments based on the cumulative percentages you calculated.
5. Create a key to show which shading or colour corresponds to each certificate.
Full Answer
**Calculations:**
**2008 (Total 500):**
U: (100/500)*100 = 20%
PG: (150/500)*100 = 30%
12A: (120/500)*100 = 24%
15: (80/500)*100 = 16%
18: (50/500)*100 = 10%
(Check: 20+30+24+16+10 = 100%)
**2018 (Total 650):**
U: (80/650)*100 ≈ 12.3%
PG: (180/650)*100 ≈ 27.7%
12A: (200/650)*100 ≈ 30.8%
15: (150/650)*100 ≈ 23.1%
18: (40/650)*100 ≈ 6.1%
(Check: 12.3+27.7+30.8+23.1+6.1 = 100%)
**Chart:**
Two bars, one for 2008 and one for 2018, both reaching 100% on the y-axis.
**2008 Bar:**
- U section from 0% to 20%
- PG section from 20% to 50%
- 12A section from 50% to 74%
- 15 section from 74% to 90%
- 18 section from 90% to 100%
**2018 Bar:**
- U section from 0% to 12.3%
- PG section from 12.3% to 40%
- 12A section from 40% to 70.8%
- 15 section from 70.8% to 93.9%
- 18 section from 93.9% to 100%
A key is needed to show which colour/shading represents each certificate.
A percentage composite bar chart (or stacked bar chart) shows how a whole is divided into parts, where the whole is always 100%.
**Step 1: Calculate Percentages**
First, we must convert the raw numbers from Table 1 into percentages for each year.
For 2008 (Total = 500):
- U: (100/500) × 100 = 20%
- PG: (150/500) × 100 = 30%
- 12A: (120/500) × 100 = 24%
- 15: (80/500) × 100 = 16%
- 18: (50/500) × 100 = 10%
For 2018 (Total = 650):
- U: (80/650) × 100 ≈ 12.3%
- PG: (180/650) × 100 ≈ 27.7%
- 12A: (200/650) × 100 ≈ 30.8%
- 15: (150/650) × 100 ≈ 23.1%
- 18: (40/650) × 100 ≈ 6.1%
**Step 2: Draw the Chart**
- Draw two bars, one for each year, side-by-side. The vertical axis should be "Percentage (%)" and go from 0 to 100.
- For the 2008 bar, the first section (U) goes from 0 to 20%. The next (PG) goes from 20% to 50% (20+30). The next (12A) goes from 50% to 74% (50+24), and so on, until the last section finishes at 100%.
- Repeat for the 2018 bar using its calculated percentages.
- Include a key to identify the segments.
Common mistakes
✗ Drawing a regular bar chart with raw numbers instead of percentages.
✗ Drawing a grouped bar chart instead of a composite (stacked) one.
✗ Calculation errors when finding percentages.
✗ Forgetting to include a key.
Practice the full AQA GCSE Statistics Foundation Tier Paper 1
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