Exercise Set 10.5 Class 9 Maths Ganita Manjari Part 2

 

Exercise Set 10.5

How Quantities Combine: Understanding Data

Question 1

The smartwatch 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., as shown in the following table.

Table 10.3: Average number of hours spent per day (Monday–Friday) lying down, sitting, and standing or moving around, etc., of 5 people.

Person	Lying down (hours)	Sitting (hours)	Standing or moving around, etc. (hours)
Pavani (Patient)	20	3	1
Raghu (Nurse)	7	4	13
Zakir (Teacher)	8	6	10
Sahana (Student)	—	—	—
Julie (occupation not given)	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 below based on the tabular data.

Solutions

(i) A reasonable guess for Sahana

One reasonable estimate for a student is 8 hours lying down, 7 hours sitting, and 9 hours standing or moving around. These add up to 24 hours.

Person	Lying down	Sitting	Standing or moving around, etc.	Total
Sahana (Student) — suggested estimate	8 hours	7 hours	9 hours	24 hours

Note: The textbook asks for a reasonable guess, so Sahana’s row does not have one unique correct answer. The suggested values above are an example; other sensible values that total 24 hours may also be acceptable.

(ii) What might Julie do?

Julie spends 8 hours lying down, 10 hours sitting, and 6 hours standing or moving around. She might have a mostly seated job, such as an office worker, driver, or someone who studies for long hours. The data alone cannot identify her exact occupation.

(iii) Completed 100% stacked chart

Each person’s daily total is 24 hours, so the chart shows the share of the day in each state. The segments are calculated as (hours ÷ 24) × 100.

Lying down Sitting Standing/moving around

Pavani
(Patient)

Raghu
(Nurse)

Zakir
(Teacher)

Sahana
(Student)

Julie
(occupation unknown)

0%25%50%75%100%

Note: Sahana’s bar uses the suggested estimate (8 h, 7 h, 9 h). The other bars use the given table values.

Percentage calculations

Person	Lying down	Sitting	Standing/moving
Pavani	20/24 × 100 = 83.33%	3/24 × 100 = 12.5%	1/24 × 100 = 4.17%
Raghu	7/24 × 100 = 29.17%	4/24 × 100 = 16.67%	13/24 × 100 = 54.17%
Zakir	8/24 × 100 = 33.33%	6/24 × 100 = 25%	10/24 × 100 = 41.67%
Sahana (suggested)	8/24 × 100 = 33.33%	7/24 × 100 = 29.17%	9/24 × 100 = 37.5%
Julie	8/24 × 100 = 33.33%	10/24 × 100 = 41.67%	6/24 × 100 = 25%

Educational note: the percentages may total 99.99% or 100.01% in some rows because values are rounded to two decimal places.