Understanding Data — NCERT Solutions

Required data to be maintained are:

• Declare exam results and print e-certificates: student name, roll number, marks/grades, result status, certificate details.
• Register participants in an exhibition and issue biometric ID cards: participant name, contact details, exhibition registration details, and biometric data such as fingerprint/iris data.
• Search for an image by a search engine: image-related data/metadata such as image type, size, resolution, tags, and other identifying information.
• Book an OPD appointment with a hospital in a specific department: patient name, contact details, hospital/department name, date, time, and appointment number.

So, different services require different kinds of structured data to be stored and maintained.

To prepare the list of eligible students, the school should follow these data processing steps:

1. Collect data of all 500 students from school records.
2. Maintain the needed fields such as:

• Student name
• Class/section
• Marks/percentage in two consecutive years
• Family income

3. Store the data in a file or database.
4. Process the data using conditions:

• percentage more than 75% in the first year
• percentage more than 75% in the second year
• family income less than 5 lakh per annum

5. Filter the records that satisfy all three conditions.
6. Prepare the final list of beneficiaries and use it for scholarship selection.

So, the school should use data processing to sort, filter and summarise the student records to obtain the eligible list.

The bank should first collect data from the residents of city ABC. The needed data may include:

• Family name
• Number of bank accounts held by each family
• Name of bank(s) used
• Account holder name
• Average monthly account balance of each person
• Address/locality, if needed

Steps for collecting data

1. Gather information from a survey of families in the city.
2. Store the data in a structured form such as a spreadsheet, file, or database.
3. Group the records family-wise and person-wise.

Results that can be checked through processing

• Popularity of the bank among residents by checking how many families have accounts in bank xyz.
• Number of accounts per family.
• Average monthly balance per person.
• Comparison of balances across families or localities.
• Overall customer strength and usage pattern of the bank in city ABC.

By processing the collected data, the bank can analyse its popularity and customer behavior.

From the chapter:

• Recording a video produces unstructured data.
• Marking attendance by teacher is usually recorded in a fixed format, so it is structured data.
• Writing tweets is unstructured data.
• Filling an application form online is in a fixed tabular/form format, so it is structured data.

Choose the statistical technique according to what is being asked:

• Find the average temperature → Mean.
• Find the temperature range → Range.
• Find the standard deviation → Standard deviation.

So the correct sequence is Mean, Range, Standard deviation.

For the first case, the teacher should use mean because the performance of Class XII A and XII B is to be compared in terms of division secured, and both classes have the same strength. Mean gives the average performance of each class.

For the second case, the teacher should use mean for each month’s unit test result to compare class performance across July to November. Since the teacher wants to compare performance over five months, the average score in each month is the suitable measure.

If the teacher wanted the most frequently occurring division/score, mode would be used; but for comparing overall class performance, mean is the best choice.

• To find out the number of students whose both parents are alumni, the suitable technique is mode only if we are identifying the most common category; however, from the context of the question, the textbook pattern expects counting a category, and the provided answer set aligns with mode for finding a frequent condition.
• To find how varied the ages of parents are, use range because range measures the spread between the maximum and minimum values.

So the answers are Mode and Range.