NCERT Solutions Class 9 Mathematics Ganita Manjari 2 Chapter 10 How Quantities Combine Understanding Data Exercise 10.5

Exercise Set 10.5

Question 1. The smart watch data of 5 people was tracked from Monday to Friday. The recorded data tells us how many hours each person spent lying down, sitting, and standing or moving around, etc. (Table 10.3: average hours per day, Monday–Friday)
Pavani (Patient): lying down 20, sitting 3, standing/moving 1
Raghu (Nurse): 7, 4, 13
Zakir (Teacher): 8, 6, 10
Sahana (Student): ___
Julie (_________): 8, 10, 6
(i) How much time does Sahana spend per day in each of these body-states? Make a reasonable guess and fill her row in the table.
(ii) Guess what activity or work Julie could be engaged in based on the data. Find out what your classmates' guesses are.
(iii) Complete the chart based on the tabular data.
Answer:
(i) A student sleeps about 8–9 hours, sits through school, tuition, homework and meals (about 9 hours), and stands or moves for the rest (travel, games, chores).
A reasonable guess: Sahana: lying down 9 h, sitting 9 h, standing/moving 6 h (9 + 9 + 6 = 24 ✓). Other guesses such as 8, 10, 6 are fine as long as the total is 24 h.
(ii) Julie sleeps a normal 8 hours, sits for 10 hours (her largest share) and moves for only 6. So her work is mostly done sitting: an office worker (clerk, accountant, software engineer), a bank cashier, a driver or a tailor. Guesses may vary.
(iii) Each value as a share of 24 hours:
Pavani: 83.3%, 12.5%, 4.2%; Raghu: 29.2%, 16.7%, 54.2%; Zakir: 33.3%, 25%, 41.7%; Sahana: 37.5%, 37.5%, 25%; Julie: 33.3%, 41.7%, 25%.

Since every person's total is 24 h, this chart is at once a stacked chart (in hours) and a 100% stacked chart.

Teacher's Note:
1. Every row must add up to 24 hours.
2. The dominant piece of each bar hints at the kind of work.