NCERT Solutions Class 12, Computer Science, Chapter- 7, Understanding Data
Exercise
1. Identify data required to be maintained to perform the following services:
a) Declare exam results and print e-certificates
b) Register participants in an exhibition and issue biometric ID cards
c) To search for an image by a search engine
d) To book an OPD appointment with a hospital in a specific department
Solution:
a) Enrollment No. (As a Primary Key), Student Name, List of Subjects, Marks Scored, Full Marks, Grades (Optional), etc.
b) Serial No. (As a Primary Key), Biometric Details (As a Foreign Key), Name, Address, etc.
c) X Position of a pixel, Y Position of pixel, Pixels {RGB form: Red composition, blue composition, Green composition}
d) Appointment No. (As a Primary Key), Patient's Name, Dept. Name, Earlier Medication History of Patient (Optional).
2. A school having 500 students wants to identify beneficiaries of the merit-cum means scholarship, achieving more than 75% for two consecutive years and having family income less than 5 lakh per annum. Briefly describe data processing steps to be taken by the to beneficial prepare the list of school.
Solution:
Step 1 and Step 2 are essential and sufficient for the required work to be done. Step 1, will provide us with all the data in tabular form and Step 2 will enable us to short-list the required data. Data at the end of step 1 and step 2 in tabular form will be our result.
3. A bank ‘xyz’ wants to know about its popularity among the residents of a city ‘ABC’ on the basis of number of bank accounts each family has and the average monthly account balance of each person. Briefly describe the steps to be taken for collecting data and what results can be checked through processing of the collected data.
Solution:
1. Data collection
Banks already have data about customers so this step is not required.
2. Data Storage
Bank already has data stored in its database.
3. Data Processing
a) A bank employee will prepare a report using the SQL queries to get all those customers that are having accounts in that area along with the Monthly Average Balance of every customer.
b) After preparing the report the data will be compared with available customer data from other branches of this bank. This comparison will directly show the popularity of that branch in the area.
4. Identify type of data being collected/generated in the following scenarios:
a) Recording a video
b) Marking attendance by teacher
c) Writing tweets
d) Filling an application form online
Solution:
a) Recording a video requires the collection of data types known as Frames. Recording a video requires the collection of data types known as Frames.
b) To mark attendance teachers must collect data in the form of text that is either Absent or Present.
c) The most suitable data type for writing a tweet is Text.
d) The most suitable data type to be used for filling an online application is ‘Text’.
5. Consider the temperature (in Celsius) of 7 days of a week as 34, 34, 27, 28, 27, 34, 34. Identify the appropriate statistical technique to be used to calculate the following:
a) Find the average temperature.
Solution:
The average can be calculated by finding the mean.
The formula used,
m = sum of the terms / number of terms
Average Temperature = Sum of All Reading / Total number of readings
Average Temperature = \({34 + 34 + 27 + 28 + 27 + 34 + 34 \over 7 }\) = \( {218 \over 7}\) = 31.142857
The average temperature is 31.142857 C°.
b) Find the temperature Range of that week.
Solution:
Temperature Range = (Maximum Temperature - Minimum Temperature)
Temperature Range = 34 - 27 = 7
The temperature range of that week is 7 C°.
c) Find the standard deviation temperature.
Solution:
The formula used for calculating Standard Deviation: \(σ = { \sqrt{{\sum(x_i - \mu)^2 } \over N}}\)
\(\)Standard Deviation = \({[{ (2.85) ^2 + (2.85)^2 + (4.412)^2 + (3.14) + (4.14)^2 + (2.85)^2 + (2.85)^2 \over 7} ] }^1/2\)
= \([10.946]^1/2 = 3.308\)
The standard deviation of the temperature is 3.3084 C°.
6. A school teacher wants to analyse results. Identify the appropriate statistical technique to be used along with its justification for the following cases:
a) Teacher wants to compare performance in terms of division secured by students in Class XII A and Class XII B where each class strength is same.
Solution:
Mean is the statistical technique to be employed in this case because it will provide the average value of the marks of both the classes which will give us a clear understanding of the performance. Higher the average, higher the performance of the class.
b) Teacher has conducted five unit tests for that class in months July to November and wants to compare the class performance in these five months.
Solution:
Mean will be suitable technique to compare class performance months wise. Take average marks of all students per month and compare them to realize if it is increasing or decreasing.
7. Suppose annual day of your school is to be celebrated. The school has decided to felicitate those parents of the students studying in classes XI and XII, who are the alumni of the same school. In this context, answer the following questions:
a) Which statistical technique should be used to find out the number of students whose both parents are alumni of this school?
Solution:
Mean of the previous record of students whose parents are alumni.
b) How varied are the age of parents of the students of that school?
Solution:
Standard Deviation
8. For the annual day celebrations, the teacher is looking for an anchor in a class of 42 students. The teacher would make selection of an anchor on the basis of singing skill, writing skill, as well as monitoring skill.
a) Which mode of data collection should be used?
Solution:
Audition based in presence of unbiased judges.
b) How would you represent the skill of students as data?
Solution:
Number allocation over the skills presented by the candidate.
