Dictionary Rank of a Word | Permutations & Combinations

 PERMUTATIONS & COMBINATIONS Rank of the word or Dictionary order of the English words like COMPUTER, COLLEGE, SUCCESS, SOCCER, RAIN, FATHER, etc. Dictionary Rank of a Word Method of finding the Rank (Dictionary Order) of the word  “R A I N” Given word: R A I N Total letters = 4 Letters in alphabetical order: A, I, N, R No. of words formed starting with A = 3! = 6 No. of words formed starting with I = 3! = 6 No. of words formed starting with N = 3! = 6 After N there is R which is required R ----- Required A ---- Required I ---- Required N ---- Required RAIN ----- 1 word   RANK OF THE WORD “R A I N” A….. = 3! = 6 I……. = 3! = 6 N….. = 3! = 6 R…A…I…N = 1 word 6 6 6 1 TOTAL 19 Rank of “R A I N” is 19 Method of finding the Rank (Dictionary Order) of the word  “F A T H E R” Given word is :  "F A T H E R" In alphabetical order: A, E, F, H, R, T Words beginni

Lesson Plan Math Class X (Ch-14) | Statistics


lesson plan for maths class 10 chapter 14, statistics, lesson plans for mathematics teachers,  Method to write lesson plan for maths class 10,  lesson plan for mathematics grade 10, lesson plan for maths in B.Ed.

Board – CBSE



CHAPTER 14  :-  Statistics


Chapter 14 Statistics (To find mean, mode, median and frequency ogive)


This topic is divided into seven modules and are completed in ten class meetings.


Chapter 14 statistics class 9Th  or mean, mode, median of ungrouped frequency.

TEACHING AIDS:-  Green Board, Chalk,  Duster, Charts  etc.

METHODOLOGY:-  Demonstration and Lecture method

  • Introduction and method of finding mean of grouped frequency with three methods.
  • Method of finding mode of grouped frequency.
  • Method of finding median of grouped frequency.
  • Method of finding less than and more than ogive.
  • Method of finding median from less than type and more than type ogive.

Start the session by checking their previous knowledge, by asking the questions of mean , mode, median of ungrouped frequency. After this explain the topic to the students. 

S. No.


For Complete Explanation of the topic



In this chapter students will learn the method of finding the mean, mode and median of grouped and ungrouped data. Also students will work on the frequency ogive or curve.


Calculation of Mean

Now teacher will explain different methods of calculating mean with grouped and ungrouped frequency.

Mean of ungrouped data


Mean of grouped data

There are three methods of finding the mean of grouped data

(1) Direct method


(2) Assumed mean method


(3) Step Deviation method


For simple data with less calculation Direct method can be used easily. But for the data with larger terms assumed mean method or step deviation method can be use.


Explanation of finding the Missing frequency

Now teacher will explain the method of finding one or two missing frequencies in grouped and ungrouped data. Students should be given sufficient number of problems for practice.


Method of finding mode 

Here teacher will explain  the method of finding the mode with ungrouped data and with grouped data.

Median Class: Class corresponding to the highest frequency is called Model Class.

f1 is the frequency of the model class

f0 is the frequency of the class proceeding the median class

f2 is the frequency of the class succeeding the median class.


Calculation of Median

Now teacher will introduce the topic Median. First of all teacher will explain the Median class and all the abbreviations which are linked with the formula.

Median class : A class corresponding to the cumulative frequency ≥ n/2 is called median class.

l is the lower limit of median class.

 Cf is the cumulative frequency of class preceding the median class

f is the frequency of median class    


Ogive: Ogives are of two types

Less than Ogive: This graph can be made by taking upper limits towards the x - axis and cumulative frequency(less than type) towards the y-axis.

More than Ogive: This graph can be made by taking lower limits towards the y - axis and cumulative frequency(more than type) towards the y-axis.


Finding Median From the Ogive.

Here teacher will explain the complete method of finding the median by plotting less than ogive and more than ogive on the same graph paper.

Value on the x - axis corresponding to the point of intersection of less then ogive and more than ogive is called the median .

Teacher will also explain the method of finding the median for single curve.

In a single curve, Median is the value on the x-axis corresponding to the value = n/2 on the y-axis.

  • After studying this lesson students should know 
  • All formulas of finding mean of the given data.
  • All formulas of finding mode of the given data.
  • All formulas of finding median of the given data.
  • Method of finding the less than ogive and more than ogive and the median from the graph.
  • The relation between mean, mode median (Empirical formula)  
  • Students should also know the method of implementation of these formulas in simple and complex problems.
  • Review questions given by the teacher. 
  • Students should prepare the presentation on the basic concepts and formulas on statistics. 
  • Solve NCERT problems with examples.
  • solve assignment given by the teacher.

Students can extend their learning through the RESOURCE CENTRE and can find more valuable and interesting concepts on mathematics at  cbsemathematics.com

Assignment sheet will be given as home work at the end of the topic. Separate sheets which will include questions of logical thinking and Higher order thinking skills will be given to the above average students.
Class Test , Oral Test , worksheet and Assignments can be made the part of assessment.
Re-test(s) will be conducted on the basis of the performance of the students in the test.



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