Page 191 - Data Science class 10
P. 191

B.  Fill in the blanks.

               1.  The ____________________ can be determined by subtracting the first quartile (Q1) from the third quartile (Q3).

               2.  We can do data merging by applying ____________________ on the databases in frame.
               3.  ____________________ is also known as a many to one join.

               4.  Z-score is also termed as ____________________ .

               5.  A positive z-score specifies the raw score is ____________________ than the mean average.


                 Standard Questions (Section B)


            A.  Short answer type questions:
               1.  What is data merging?                                                             [CBSE Handbook]
             Ans.  The practice of combining two or more similar records into a single one is known as data merging.
               2.  Name the types of joins in database.
             Ans.  There are three types of data joins which are as follows:
                  •  One to one Joins
                  •  One to many Joins
                  •  Many to many Joins

               3.  What is Z-Score?
             Ans.  A z-score defines the position of a point in terms of its distance from the mean when it is calculated in standard
                  deviation units.
               4.  What is a percentile?
             Ans.  A percentile can be defined as the percentage of the total ordered observations at or below it.

               5.  What is the z-score of a value of 25, given a set mean of 22, and a standard deviation of 2?
             Ans.  To find the z-score, we need to divide the difference between the value 25, and the mean 22, by the standard deviation
                  of the set 2.
                     z-score =  (x – μ)
                                σ
                     Here, x = 25
                         μ = 22
                         σ = 2

                           =  25 – 22
                                2
                           = 1.5
                  This indicates that 25 is 1.5 standard deviations above the mean.

            B.  Long answer type questions:
               1.  What are the benefits of data merging?
             Ans.  There are many benefits of merging your datasets. Some of them are as follows:
                  •  Accuracy: All of the information is guaranteed to be entirely accurate when it is combined into a single set.
                  •  Completeness: All of the information is combined into one place when the sets are merged. This guarantees that the
                    set of data is complete and there are no missing pieces of information in the set.  Since everything is in one place, it
                    is easy to find and use.




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