NCERT Solutions Class 9 Mathematics Ganita Manjari 2 Chapter 10 How Quantities Combine Understanding Data Exercise 10.4

Exercise Set 10.4

Question 1. The following stacked column chart shows the number of animal species in the IUCN Red List, by class, over time.
(The IUCN Red List is a regularly updated database of the extinction risk of species worldwide.)
(i) What does the number 14,234 on the top of the column 2019 represent?
(ii) Approximately how many reptile species were in the list in 2016?
(iii) Which class(es) of species have seen a relatively small increase in count between 2007 and 2019?
Answer:
(i) In a stacked column the full height is the sum of all its pieces. So 14,234 is the total number of threatened animal species (all classes together) on the IUCN Red List in 2019.
(ii) In 2016 the Reptiles piece (second from the bottom) starts at about 1,200 (top of Mammals) and ends at about 2,300, a length of about 1,100.
So there were about 1,100 reptile species (roughly 1,000 to 1,200) on the list in 2016.
(iii) Comparing piece lengths in 2007 and 2019 (approximate): Mammals 1,100 → 1,250; Birds 1,200 → 1,500; Amphibians 1,800 → 2,200; Reptiles 400 → 1,400; Insects 600 → 1,600; Molluscs 1,000 → 2,250; Fish 1,200 → 2,700.
Mammals, birds and amphibians have changed only a little. Reptiles, insects, molluscs and fish have grown much more.

Teacher's Note:
1. A piece's value is its top minus its bottom.
2. Compare lengths, not end points, across years.

Question 2. The wickets taken by a bowler in International Cricket matches till 2025 are:
Home: Test 62, ODI 100, T20 32
Overseas: Test 172, ODI 49, T20 71
Complete the given stacked bar charts (the bar lengths can be approximate),
(i) comparing the total wickets taken at home vs. overseas;
(ii) the total wickets taken in each format.
Answer:
(i) For Home and for Overseas, lay the Test, ODI and T20 pieces end to end.
Home: 62 + 100 + 32 = 194 (Test 0–62, ODI 62–162, T20 162–194).
Overseas: 172 + 49 + 71 = 292 (Test 0–172, ODI 172–221, T20 221–292).

More wickets were taken overseas (292) than at home (194).
(ii) For each format, lay the Home and Overseas pieces end to end.
Test: 62 + 172 = 234; ODI: 100 + 49 = 149; T20: 32 + 71 = 103.

Most wickets came in Tests (234), fewest in T20s (103). Check: 194 + 292 = 234 + 149 + 103 = 486 ✓