NCERT Solutions for Class 9 Maths Chapter 10 — Exercise Set 10.4#
In a stacked bar (or column) chart, the full length of a bar shows a total, and the coloured pieces show the parts that make it up. A piece’s size is read as the difference between its top and bottom ends.
1. The following stacked column chart shows the number of animal species in the IUCN Red List, by class, over time. #
(i) What does the number 14,234 on the top of the column 2019 represent?
It is the total number of animal species on the IUCN Red List in 2019 — the sum of all the classes (mammals, reptiles, birds, insects, amphibians, molluscs, fish and others) stacked in that column.
(ii) Approximately how many reptile species were in the list in 2016?
In the 2016 column, the reptile piece (dark red, second from the bottom) runs from about 1,200 to about 2,200.
$$\text{Reptiles} \approx 2200 - 1200 = 1000$$∴ About 1,000 reptile species.
(iii) Which class(es) of species have seen a relatively small increase in count between 2007 and 2019?
Comparing the thickness of each band in 2007 and 2019:
- Mammals — about 1,100 in 2007 to about 1,250 in 2019, a small increase.
- Birds — about 1,200 to about 1,450, also a small increase.
∴ Mammals and birds grew relatively little. In contrast, fish, molluscs, insects and reptiles grew a lot.
2. The wickets taken by a bowler in International Cricket matches till 2025 are shown in the table. Complete the given stacked bar charts (the bar lengths can be approximate). #
| Test | ODI | T20 | |
|---|---|---|---|
| Home | 62 | 100 | 32 |
| Overseas | 172 | 49 | 71 |
(i) comparing the total wickets taken at home vs. overseas
$$\text{Overseas} = 172 + 49 + 71 = 292$$
The bowler took many more wickets overseas, mostly in Tests.
(ii) The total wickets taken in each format
$$\text{ODI} = 100 + 49 = 149$$
$$\text{T20} = 32 + 71 = 103$$