Page 190 - Data Science class 10
P. 190
Recap
• The practice of combining two or more similar records into a single one is known as data merging.
• In Data Science, data merging is the procedure of combining two or more datasets into a single data frame.
• We can do data merging by applying data joins on the databases in frame.
• 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.
• The z-score is important because it tells you not only about the value but also where it falls in the distribution.
• Percentile is a number that represents the percentage of scores that fall at or below that number.
• Decile is a technique that is used to divide a distribution into ten equivalent parts.
Solved Exercise
Objective Type Questions (Section A)
A. Tick ( ) the correct option.
1. The pth percentile of a distribution is such that: [CBSE Handbook]
a. p percent of the observations fall at it b. p percent of the observations fall below it
c. p percent of the observations fall at or below it d. the value is p
2. There are ____________________ types of data joins.
a. 2 b. 3
c. 4 d. 5
3. Which of the following is also called N:N relationship?
a. One to one Join b. One to many Join
c. Many to many Join d. All of these
4. According to percentiles, the median to be measured must lie in ____________________ . [CBSE Handbook]
a. 80th b. 40th
c. 50th d. 100th
5. A ____________________ z-score tells that the raw score is below the mean average.
a. positive b. negative
c. zero d. None of these
6. What measures of position divide the distribution into 10 equal parts? [CBSE Handbook]
a. Quartiles b. Deciles
c. Percentiles d. Range
188 Touchpad Data Science-X

