NCERT Solutions for Class 9 Maths Chapter 14 Statistics Exercise 14.1
Welcome to YoLearn AI's comprehensive guide on Class 9 Maths Chapter 14 Statistics Exercise 14.1! Statistics is a crucial branch of mathematics that deals with collecting, organizing, analyzing, and presenting data. In Exercise 14.1, you will focus on the foundational step of any statistical analysis: data collection. By mastering this exercise, you will learn to distinguish between Primary Data and Secondary Data. These basic concepts are highly scoring in CBSE school exams and serve as building blocks for high school and university statistics. Let us work together step-by-step with your YoLearn AI Tutor on this chapter!
Understanding Data: The Foundation of Statistics
Every day, we are surrounded by information in the form of numbers, tables, and graphs. Whether it is cricket scores, weather forecasts, or class attendance, these facts or figures collected with a definite purpose are called Data.
Before we analyze data, we must collect it. In CBSE Class 9, data collection is classified into two main types based on its source:
- Primary Data: When an investigator collects information directly with a specific objective in mind, the data obtained is first-hand. This is highly reliable and specific to the investigator's goal.
- Secondary Data: When information is gathered from a pre-existing source (like books, internet, government reports, or newspapers) where someone else has already processed the data, it is called secondary data.
Primary Data vs. Secondary Data
| Aspect | Details |
|---|---|
| Definition | Obtained from an existing source which was collected by someone else. |
| Reliability | Relatively less reliable; needs careful cross-checking. |
| Time & Cost | Quick and inexpensive to obtain as it is already published. |
| Examples | Using literacy rates published in a census report. |
How to Classify Data: A Step-by-Step Approach
- Identify the Investigator — Determine who is compiling the mathematical analysis or answering the question.
- Trace the Data Source — Check if the investigator physically collected the data themselves (Primary) or read it from an existing record (Secondary).
- Assess the Purpose — Analyze if the data was collected with a unique, custom objective in mind from scratch.
- Make the Final Classification — Label the data clearly as Primary Data or Secondary Data based on your findings.
Board Exam Tips & Common Confusions
Students often lose marks in Exercise 14.1 because they rush through the definitions.
- The Golden Rule: Always ask yourself, 'Did the investigator physically count or measure this, or did they copy it from somewhere?' If they copied it, it is always secondary data.
- Writing the Answer: In your CBSE exam, do not just write 'Primary' or 'Secondary'. Always provide a one-line explanation to secure full marks. For example, write: 'This is primary data because the information is collected directly by the investigator themselves.'
Practice Questions with Solutions
- Q: Give five examples of data that you can collect from your day-to-day life. A: Step 1: Think of everyday situations where you can count or observe numerical values. Step 2: List five distinct examples. 1. Number of students in your classroom. 2. The monthly electricity bills of your house for the last one year. 3. Heights of 15 plants in your garden. 4. Runs scored by Virat Kohli in his last 10 ODI matches (from internet/TV). 5. Number of fans and tube lights in each room of your house. Final answer: These five items represent real-life numerical data.
- Q: Classify the five examples you collected in the previous question as primary or secondary data. A: Step 1: Look at each item and see who collected it. Step 2: Classify based on original collection: - Number of students in classroom: Primary Data (collected directly by you). - Monthly electricity bills of your house: Primary Data (collected directly from your home bills). - Heights of plants in your garden: Primary Data (measured directly by you). - Runs scored by Virat Kohli: Secondary Data (obtained from cricket websites/TV records). - Number of fans and lights in each room: Primary Data (counted directly by you). Final answer: Items 1, 2, 3, and 5 are Primary Data. Item 4 is Secondary Data.
- Q: State whether the following is primary or secondary data: 'Data collected by a student from a school register regarding the attendance of students.' A: Step 1: Identify the investigator. Here, it is the student. Step 2: Identify the source of information. The source is the school register. Step 3: Since the school register was compiled by the class teacher earlier and the student is merely extracting it, the data is not first-hand. Final answer: This is Secondary Data because the student obtained the information from an already existing school record.
- Q: A researcher wants to know the average monthly expenditure of 10 families in a locality. She visits each family and records their monthly spending. Classify this data. A: Step 1: Identify the investigator. It is the researcher. Step 2: Identify how the data is gathered. The researcher personally visits each household to collect the exact expenditure values. Step 3: Since the data is collected first-hand for this specific research objective, it is primary. Final answer: This is Primary Data as it was collected directly by the investigator.
Frequently Asked Questions
What is the main difference between primary and secondary data?
Primary data is collected directly by the investigator for the first time for a specific objective. Secondary data is already compiled by some other agency or person and is reused by the investigator.
Can secondary data be more reliable than primary data?
Generally, primary data is considered more reliable and accurate because the investigator has control over the collection process. However, secondary data collected by reputed government agencies (like census data) is also highly authentic.
Is CBSE Class 9 Maths Exercise 14.1 important for exams?
Yes, Exercise 14.1 is important because it introduces the basic terminology of statistics. Questions from this exercise are frequently asked as 1-mark or 2-mark conceptual questions in CBSE school exams.