What do you observe? What do you find interesting in the data/graphs? Discuss with others.
Step-by-step solution
| Lighting | Cooling | Kitchen appliances | Other appliances | |
|---|---|---|---|---|
| 2005 | 360 | 300 | 120 | 220 |
| 2025 | 220 | 800 | 460 | 520 |
Idea: Read both charts: the stacked bar shows actual amounts, the 100% bar shows shares. A share can fall even when the amount rises, because the total has grown.
- Total: from 1000 to 2000 units a day: the house uses twice as much electricity.½ mark
- Cooling rose from 300 to 800 units (more than 2.5 times) and from 30% to 40%: it is now the largest use, perhaps because of hotter summers and more air conditioners.1 mark
- Lighting fell from 360 to 220 units even though the total doubled, perhaps because LED bulbs use much less power. Its share dropped sharply, from 36% to 11%.½ mark
- Kitchen appliances grew almost 4 times (120 → 460, 12% → 23%) and other appliances rose from 220 to 520 (22% → 26%): more gadgets such as microwaves, washing machines and chargers. Interesting point: other appliances more than doubled in amount, yet their share rose only a little, because the total also doubled.1 mark
Answer to write in the exam
Total: 1000 → 2000 units (doubled)
Cooling: 300 → 800 units, 30% → 40% (largest share)
Lighting: 360 → 220 units, 36% → 11% (fell)
Kitchen: 120 → 460 units, 12% → 23%; other: 220 → 520 units, 22% → 26%
∴ Cooling and appliances drive the increase; lighting uses less
Common mistakes that cost marks
- Saying lighting fell from 36% to 11% ‘units’. The 100% chart gives shares; the units are 360 and 220.
- Thinking other appliances’ use barely changed because its share moved only from 22% to 26%; in units it more than doubled.
- Comparing bar lengths of the 100% chart to say the total doubled; a 100% chart cannot show totals.
How this can come in the exam
Assertion (A): The share of an item in a 100% stacked bar can fall even when the amount spent on it rises.
Reason (R): The share also depends on the total, which may grow faster.
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Show answer
(A) Both A and R are true, and R is the correct explanation of A.
Share = amounttotal; if the total grows faster than the amount, the share falls. R explains A.
Try one yourself
A family spent ₹2000 of ₹10000 on fuel last year and ₹2400 of ₹16000 this year. Did fuel spending rise? Did its share rise?
Show answer
Amount rose (₹2000 → ₹2400) but the share fell: 20% → 15%.
More questions like this
- The 100% stacked bar below compares the proportion of flowers blooming in Fatima’s garden and Naveen’s garden across seasons. Which of the following statements can be inferred from this chart?
(Hint: Find out the blooms per season in each garden if both the gardens had the same total number of blooms over the year. Similarly find out what happens if the totals are very different.) - 1. What does this say about the scope of the stacked bars and 100% stacked bars?
2. Given a stacked bar chart can we make a corresponding 100% stacked bar chart?
3. Given a 100% stacked bar chart can we make a corresponding stacked bar chart?
4. What kind of inferences or comparisons can be made from a stacked bar chart and in a 100% stacked bar chart? - The following chart shows the time spent on different activities in a day by the average Indian. What do you notice? What do you wonder about?
- 1. What do you find interesting in the chart above? What can you infer? Discuss.
2. Do you remember the sleep time over age trend that you studied last year? Does that trend align with this chart?
3. Can you explain why the learning time of people in the age group 15 – 24 has reduced significantly compared to that of the age group 6 – 14?
4. Do adults spend about an equal amount of time in paid and unpaid work? What do you think? - What type of chart is this — a stacked bar chart or a 100% stacked bar chart?