{"id":9140,"date":"2026-06-01T21:33:48","date_gmt":"2026-06-01T21:33:48","guid":{"rendered":"https:\/\/kapdec.com\/help\/?p=9140"},"modified":"2026-06-01T21:33:48","modified_gmt":"2026-06-01T21:33:48","slug":"mean-mode-median-graphical-representation-of-frequency-distribution","status":"publish","type":"post","link":"https:\/\/kapdec.com\/help\/mean-mode-median-graphical-representation-of-frequency-distribution\/","title":{"rendered":"Mean, Mode, Median Graphical Representation Of Frequency Distribution"},"content":{"rendered":"<h2><strong>Unit: <\/strong><strong>Statistics and Probability<\/strong><\/h2>\n<h3><strong>Chapter: <\/strong><strong>Mean, Mode, Median Graphical Representation of Frequency Distribution<\/strong><\/h3>\n<p><em>Reference: &#8211; Introduction to Statistics, Measures of Central Tendency, Mean (Arithmetic Mean), Median, Mode, Graphical Representation: Bar Graphs, Histograms, Frequency Polygons, Ogives (Cumulative Frequency Curves), Comparison and Application<\/em><\/p>\n<p><strong>After studying this chapter, you should be able to understand:<\/strong><\/p>\n<ul>\n<li>The concepts of mean, median, and mode as measures of central tendency.<\/li>\n<li>How to calculate mean, median, and mode for grouped and ungrouped data.<\/li>\n<li>Various methods of graphical representation of data.<\/li>\n<li>How to interpret and compare different types of graphs.<\/li>\n<\/ul>\n<p><strong>Introduction to Statistics<\/strong><\/p>\n<p><strong><u>Definition<\/u><\/strong><\/p>\n<p>Statistics is the branch of mathematics that deals with the collection, organization, analysis, interpretation, and presentation of data. It helps in summarizing and describing the main features of a collection of information.<\/p>\n<p>The primary goal is to make sense of data and draw meaningful conclusions from it.<\/p>\n<p><strong>[Importance of Statistics]<\/strong><\/p>\n<ul>\n<li>Used in various fields like economics, business, science, and social sciences.<\/li>\n<li>Helps in decision-making based on data analysis.<\/li>\n<li>Essential for research and forecasting.<\/li>\n<li>Enables comparison between different sets of data.<\/li>\n<\/ul>\n<p><strong>Example<\/strong><\/p>\n<p><strong>Data Set:<\/strong>&nbsp;The test scores of 10 students: 85, 90, 78, 92, 88, 76, 95, 89, 84, 91.<br \/>\nWe can find the average score, the most frequent score, and the middle score<\/p>\n<p><strong>[Subtopics]<\/strong><\/p>\n<p><strong>1. Types of Data<\/strong><\/p>\n<ul>\n<li><strong>Ungrouped Data:<\/strong>&nbsp;Raw data without any intervals.<\/li>\n<li><strong>Grouped Data:<\/strong>&nbsp;Data organized into classes or intervals.<\/li>\n<\/ul>\n<p><strong>Key Points:<\/strong><\/p>\n<ul>\n<li><strong>Frequency:<\/strong>&nbsp;The number of times a particular value occurs.<\/li>\n<li><strong>Class Interval:<\/strong>&nbsp;A range of values used for grouping data.<\/li>\n<li><strong>Class Mark:<\/strong>&nbsp;The midpoint of a class interval.<\/li>\n<\/ul>\n<p><strong>Measures of Central Tendency<\/strong><\/p>\n<p><strong>[Definition]<\/strong><\/p>\n<p>Measures of central tendency are statistical measures that represent the center point or typical value of a dataset. The three main measures are Mean, Median, and Mode.<\/p>\n<p><strong>[Importance of Central Tendency]<\/strong><\/p>\n<ul>\n<li>Provides a single value that represents the entire dataset.<\/li>\n<li>Helps in summarizing large sets of data.<\/li>\n<li>Useful for comparing different datasets.<\/li>\n<li>Forms the basis for more complex statistical analysis.<\/li>\n<\/ul>\n<p><strong>Examples<\/strong><\/p>\n<ul>\n<li>For the data set: 2, 3, 3, 5, 7, the mean is 4, the median is 3, and the mode is 3.<\/li>\n<\/ul>\n<p><strong>[Subtopics]<\/strong><\/p>\n<p><strong>1. Mean (Arithmetic Mean)<\/strong><\/p>\n<p>The mean is the average of all the values in the dataset.<\/p>\n<ul>\n<li><strong>For Ungrouped Data:<\/strong>&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"38\" src=\"https:\/\/app.kapdec.com\/questions-images\/Zp3kYMlJMCOh1765108298.gif?time=1765108299\" width=\"98\" \/>, where&nbsp;<em>&sum;x<\/em>&nbsp;is the sum of all values and n is the number of values.<\/li>\n<li><strong>For Grouped Data:<\/strong>&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"41\" src=\"https:\/\/app.kapdec.com\/questions-images\/wOaOKSEoyOuk1765108299.gif?time=1765108300\" width=\"116\" \/>, where&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"27\" src=\"https:\/\/app.kapdec.com\/questions-images\/f15aOILiplKf1765108299.gif?time=1765108300\" width=\"14\" \/>&nbsp;is the frequency of the i-th class and&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"27\" src=\"https:\/\/app.kapdec.com\/questions-images\/XYh9O1Hug4vB1765108299.gif?time=1765108300\" width=\"17\" \/>&nbsp;is the class mark.<\/li>\n<\/ul>\n<p><strong>2. Median<\/strong><\/p>\n<p>The median is the middle value when the data is arranged in ascending or descending order.<\/p>\n<ul>\n<li><strong>For Ungrouped Data:<\/strong>\n<ul style=\"list-style-type:circle\">\n<li>If n is odd: Median =&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"37\" src=\"https:\/\/app.kapdec.com\/questions-images\/61lBfiR4Sw7P1765108300.gif?time=1765108300\" width=\"61\" \/>&nbsp;value.<\/li>\n<li>If n is even: Median = average of&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"35\" src=\"https:\/\/app.kapdec.com\/questions-images\/5cTg1B2e3CRD1765108300.gif?time=1765108300\" width=\"42\" \/>&nbsp;and&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"35\" src=\"https:\/\/app.kapdec.com\/questions-images\/7eqBBzY3VPGG1765108300.gif?time=1765108301\" width=\"77\" \/>&nbsp;values.<\/li>\n<\/ul>\n<\/li>\n<li><strong>For Grouped Data:<\/strong>&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"48\" src=\"https:\/\/app.kapdec.com\/questions-images\/NRQCnhQklE9f1765108300.gif?time=1765108301\" width=\"214\" \/>, where l is the lower limit of the median class, cf is the cumulative frequency of the class preceding the median class, f is the frequency of the median class, and h is the class width.<\/li>\n<\/ul>\n<p><strong>3. Mode<\/strong><\/p>\n<p>The mode is the value that appears most frequently in the dataset.<\/p>\n<ul>\n<li><strong>For Ungrouped Data:<\/strong>&nbsp;The value with the highest frequency.<\/li>\n<li><strong>For Grouped Data:<\/strong>&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"41\" src=\"https:\/\/app.kapdec.com\/questions-images\/lfiQuonP1FOS1765108300.gif?time=1765108301\" width=\"231\" \/>, where l is the lower limit of the modal class,&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"27\" src=\"https:\/\/app.kapdec.com\/questions-images\/gBFhpCtBDZJS1765108300.gif?time=1765108301\" width=\"16\" \/>&nbsp;is the frequency of the modal class,&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"27\" src=\"https:\/\/app.kapdec.com\/questions-images\/i8hrCPLbYe3E1765108301.gif?time=1765108301\" width=\"17\" \/>&nbsp;is the frequency of the class preceding the modal class,&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"27\" src=\"https:\/\/app.kapdec.com\/questions-images\/x5rkC1vmKBB51765108301.gif?time=1765108301\" width=\"17\" \/>&nbsp;is the frequency of the class succeeding the modal class, and h is the class width.<\/li>\n<\/ul>\n<p><strong>Mean (Arithmetic Mean)<\/strong><\/p>\n<p><strong>[Definition]<\/strong><\/p>\n<p>The arithmetic mean is the sum of all values divided by the number of values. It is the most commonly used measure of central tendency.<\/p>\n<p><strong>[Importance of Mean]<\/strong><\/p>\n<ul>\n<li>Uses all values in the dataset.<\/li>\n<li>Easy to understand and calculate.<\/li>\n<li>Suitable for further statistical analysis.<\/li>\n<\/ul>\n<p><strong>Examples<\/strong><\/p>\n<ul>\n<li>Find the mean of the numbers: 10, 20, 30, 40, 50.<\/li>\n<\/ul>\n<p><strong>[Subtopics]<\/strong><\/p>\n<p><strong>1. Calculation for Ungrouped Data<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"49\" src=\"https:\/\/app.kapdec.com\/questions-images\/6TxAfBUUd3PS1765108301.gif?time=1765108302\" width=\"393\" \/><\/p>\n<p><strong>2. Calculation for Grouped Data<\/strong><\/p>\n<p>Using the formula&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"41\" src=\"https:\/\/app.kapdec.com\/questions-images\/DrCJhPl5G6Fs1765108301.gif?time=1765108302\" width=\"116\" \/>.<\/p>\n<p><strong>Median<\/strong><\/p>\n<p><strong>[Definition]<\/strong><\/p>\n<p>The median is the value that separates the higher half from the lower half of the data set. It is less affected by extreme values (outliers) than the mean.<\/p>\n<p><strong>[Importance of Median]<\/strong><\/p>\n<ul>\n<li>Provides a better measure for skewed distributions.<\/li>\n<li>Useful when extreme values are present.<\/li>\n<li>Easy to find for ordinal data.<\/li>\n<\/ul>\n<p><strong>Examples<\/strong><\/p>\n<ul>\n<li>Find the median of: 12, 15, 18, 20, 25.<\/li>\n<\/ul>\n<p><strong>[Subtopics]<\/strong><\/p>\n<p><strong>1. Calculation for Ungrouped Data<\/strong><\/p>\n<p>Arrange in order: 12, 15, 18, 20, 25. n=5 (odd), so Median = 3rd value = 18.<\/p>\n<p><strong>2. Calculation for Grouped Data<\/strong><\/p>\n<p>Using the formula&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"48\" src=\"https:\/\/app.kapdec.com\/questions-images\/3Gpa06sU0JpG1765108301.gif?time=1765108302\" width=\"214\" \/>.<\/p>\n<p><strong>Mode<\/strong><\/p>\n<p><strong>[Definition]<\/strong><\/p>\n<p>The mode is the value that occurs most frequently in the data set. A dataset may have one mode, more than one mode, or no mode at all.<\/p>\n<p><strong>[Importance of Mode]<\/strong><\/p>\n<ul>\n<li>Useful for categorical data.<\/li>\n<li>Helps in identifying the most popular or common value.<\/li>\n<li>Easy to find for nominal data.<\/li>\n<\/ul>\n<p><strong>Examples<\/strong><\/p>\n<ul>\n<li>Find the mode of: 2, 3, 4, 4, 5, 5, 5, 6, 7.<\/li>\n<\/ul>\n<p><strong>[Subtopics]<\/strong><\/p>\n<p><strong>1. Calculation for Ungrouped Data<\/strong><\/p>\n<p>The value 5 appears three times, so Mode = 5.<\/p>\n<p><strong>2. Calculation for Grouped Data<\/strong><\/p>\n<p>Using the formula&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"41\" src=\"https:\/\/app.kapdec.com\/questions-images\/XlhkvoUa9J6z1765108301.gif?time=1765108302\" width=\"231\" \/>.<\/p>\n<p><strong>Graphical Representation of Frequency Distribution<\/strong><\/p>\n<p><strong>[Definition]<\/strong><\/p>\n<p>Graphical representation involves displaying data in visual forms such as graphs and charts. This makes it easier to understand patterns, trends, and comparisons in the data.<\/p>\n<p><strong>[Importance of Graphical Representation]<\/strong><\/p>\n<ul>\n<li>Provides a quick overview of the data.<\/li>\n<li>Helps in identifying patterns and outliers.<\/li>\n<li>Makes complex data more understandable.<\/li>\n<li>Useful for presentations and reports.<\/li>\n<\/ul>\n<p><strong>Examples<\/strong><\/p>\n<ul>\n<li>Represent the frequency distribution of test scores using a histogram.<\/li>\n<\/ul>\n<p><strong>[Subtopics]<\/strong><\/p>\n<p><strong>1. Bar Graph<\/strong><\/p>\n<p>A graph that uses bars to represent frequencies of different categories. The bars can be vertical or horizontal.<\/p>\n<p><strong>2. Histogram<\/strong><\/p>\n<p>A graph that uses bars to represent frequencies of continuous data in class intervals. There are no gaps between the bars.<\/p>\n<p><strong>3. Frequency Polygon<\/strong><\/p>\n<p>A line graph formed by joining the midpoints of the tops of the bars in a histogram.<\/p>\n<p><strong>4. Ogive (Cumulative Frequency Curve)<\/strong><\/p>\n<p>A graph that represents cumulative frequencies for class intervals. It can be &quot;less than&quot; or &quot;more than&quot; type.<\/p>\n<p><strong>Comparison and Application<\/strong><\/p>\n<p><strong>[Definition]<\/strong><\/p>\n<p>This involves comparing the different measures of central tendency and graphical representations to choose the most appropriate one for a given dataset. It also includes applying these concepts to solve real-world problems.<\/p>\n<p><strong>[Importance of Comparison and Application]<\/strong><\/p>\n<ul>\n<li>Helps in selecting the best measure for a given situation.<\/li>\n<li>Enhances critical thinking and analytical skills.<\/li>\n<li>Prepares for practical data analysis in various fields.<\/li>\n<\/ul>\n<p><strong>Examples<\/strong><\/p>\n<ul>\n<li>Determine which measure of central tendency is most appropriate for a given dataset.<\/li>\n<\/ul>\n<p><strong>[Subtopics]<\/strong><\/p>\n<p><strong>1. When to Use Mean, Median, or Mode<\/strong><\/p>\n<ul>\n<li><strong>Mean:<\/strong>&nbsp;When data is symmetric and without outliers.<\/li>\n<li><strong>Median:<\/strong>&nbsp;When data is skewed or has outliers.<\/li>\n<li><strong>Mode:<\/strong>&nbsp;When dealing with categorical data or identifying the most frequent value.<\/li>\n<\/ul>\n<p><strong>2. Choosing the Right Graph<\/strong><\/p>\n<ul>\n<li><strong>Bar Graph:<\/strong>&nbsp;For categorical data.<\/li>\n<li><strong>Histogram:<\/strong>&nbsp;For continuous data.<\/li>\n<li><strong>Frequency Polygon:<\/strong>&nbsp;To show trends in continuous data.<\/li>\n<li><strong>Ogive:<\/strong>&nbsp;To determine medians, quartiles, and percentiles.<\/li>\n<\/ul>\n<p><strong>[Example: -]<\/strong><\/p>\n<p><strong>Problem Statement:<\/strong><br \/>\nThe following table shows the distribution of marks obtained by 50 students in a mathematics test.<\/p>\n<table cellspacing=\"0\" style=\"border-collapse:collapse\">\n<thead>\n<tr>\n<td>\n<p>Marks (Class Interval)<\/p>\n<\/td>\n<td>\n<p>0-10<\/p>\n<\/td>\n<td>\n<p>10-20<\/p>\n<\/td>\n<td>\n<p>20-30<\/p>\n<\/td>\n<td>\n<p>30-40<\/p>\n<\/td>\n<td>\n<p>40-50<\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\n<p>Number of Students (f)<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>10<\/p>\n<\/td>\n<td>\n<p>18<\/p>\n<\/td>\n<td>\n<p>12<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>a) Find the mean marks.<br \/>\nb) Find the median marks.<br \/>\nc) Find the modal marks.<br \/>\nd) Draw a histogram and frequency polygon for the data.<\/p>\n<p><strong>Question:<\/strong>&nbsp;Solve parts (a) to (c) and describe the construction for (d). Prove your answers by providing a step-by-step solution and giving&nbsp;<strong>three independent reasons<\/strong>&nbsp;supporting your conclusion for part (a) from these domains:&nbsp;<strong>(A) Direct Formula Application, (B) Assumed Mean Method, (C) Step-Deviation Method.<\/strong><\/p>\n<p><strong>[Solution: -]<\/strong><\/p>\n<p><strong>Given:<\/strong>&nbsp;Frequency distribution table.<\/p>\n<p><strong>Step 1: Prepare the table for calculations.<\/strong><br \/>\nWe need class marks (x_i) for mean.<\/p>\n<table cellspacing=\"0\" style=\"border-collapse:collapse\">\n<thead>\n<tr>\n<td>\n<p>Class Interval<\/p>\n<\/td>\n<td>\n<p>Frequency (f_i)<\/p>\n<\/td>\n<td>\n<p>Class Mark (x_i)<\/p>\n<\/td>\n<td>\n<p>f_i * x_i<\/p>\n<\/td>\n<td>\n<p>Cumulative Frequency (cf)<\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\n<p>0-10<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>25<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>10-20<\/p>\n<\/td>\n<td>\n<p>10<\/p>\n<\/td>\n<td>\n<p>15<\/p>\n<\/td>\n<td>\n<p>150<\/p>\n<\/td>\n<td>\n<p>15<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>20-30<\/p>\n<\/td>\n<td>\n<p>18<\/p>\n<\/td>\n<td>\n<p>25<\/p>\n<\/td>\n<td>\n<p>450<\/p>\n<\/td>\n<td>\n<p>33<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>30-40<\/p>\n<\/td>\n<td>\n<p>12<\/p>\n<\/td>\n<td>\n<p>35<\/p>\n<\/td>\n<td>\n<p>420<\/p>\n<\/td>\n<td>\n<p>45<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>40-50<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>45<\/p>\n<\/td>\n<td>\n<p>225<\/p>\n<\/td>\n<td>\n<p>50<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>Total<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>&Sigma;f_i = 50<\/strong><\/p>\n<\/td>\n<td>&nbsp;<\/td>\n<td>\n<p><strong>&Sigma;f_i x_i = 1270<\/strong><\/p>\n<\/td>\n<td>&nbsp;<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><strong>a) Find the mean marks.<\/strong><\/p>\n<p><strong>(A) Direct Formula Application<\/strong><br \/>\nMean using direct method:&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"41\" src=\"https:\/\/app.kapdec.com\/questions-images\/WRdjDi1v8t3V1765108302.gif?time=1765108303\" width=\"74\" \/><br \/>\n<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"49\" src=\"https:\/\/app.kapdec.com\/questions-images\/G8prav6JPpqD1765108302.gif?time=1765108303\" width=\"145\" \/>So, the mean marks are&nbsp;<strong>25.4<\/strong>.<\/p>\n<p><strong>(B) Assumed Mean Method<\/strong><br \/>\nLet Assumed Mean (A) = 25.<br \/>\nCalculate deviations d_i = x_i &#8211; A.<\/p>\n<table cellspacing=\"0\" style=\"border-collapse:collapse\">\n<thead>\n<tr>\n<td>\n<p>x_i<\/p>\n<\/td>\n<td>\n<p>f_i<\/p>\n<\/td>\n<td>\n<p>d_i = x_i &#8211; 25<\/p>\n<\/td>\n<td>\n<p>f_i * d_i<\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>-20<\/p>\n<\/td>\n<td>\n<p>-100<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>15<\/p>\n<\/td>\n<td>\n<p>10<\/p>\n<\/td>\n<td>\n<p>-10<\/p>\n<\/td>\n<td>\n<p>-100<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>25<\/p>\n<\/td>\n<td>\n<p>18<\/p>\n<\/td>\n<td>\n<p>0<\/p>\n<\/td>\n<td>\n<p>0<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>35<\/p>\n<\/td>\n<td>\n<p>12<\/p>\n<\/td>\n<td>\n<p>10<\/p>\n<\/td>\n<td>\n<p>120<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>45<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>20<\/p>\n<\/td>\n<td>\n<p>100<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>Total<\/strong><\/p>\n<\/td>\n<td>&nbsp;<\/td>\n<td>&nbsp;<\/td>\n<td>\n<p><strong>&Sigma;f_i d_i = 20<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Mean =&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"41\" src=\"https:\/\/app.kapdec.com\/questions-images\/6gWn9qoYL2Am1765108302.gif?time=1765108303\" width=\"324\" \/><br \/>\nThis confirms the mean.<\/p>\n<p><strong>(C) Step-Deviation Method<\/strong><br \/>\nLet Assumed Mean (A) = 25. Class width (h) = 10.<br \/>\nCalculate&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"37\" src=\"https:\/\/app.kapdec.com\/questions-images\/G8JBEARno4Hl1765108302.gif?time=1765108303\" width=\"77\" \/>.<\/p>\n<table cellspacing=\"0\" style=\"border-collapse:collapse\">\n<thead>\n<tr>\n<td>\n<p>x_i<\/p>\n<\/td>\n<td>\n<p>f_i<\/p>\n<\/td>\n<td>\n<p>u_i = (x_i &#8211; 25)\/10<\/p>\n<\/td>\n<td>\n<p>f_i * u_i<\/p>\n<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>-2<\/p>\n<\/td>\n<td>\n<p>-10<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>15<\/p>\n<\/td>\n<td>\n<p>10<\/p>\n<\/td>\n<td>\n<p>-1<\/p>\n<\/td>\n<td>\n<p>-10<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>25<\/p>\n<\/td>\n<td>\n<p>18<\/p>\n<\/td>\n<td>\n<p>0<\/p>\n<\/td>\n<td>\n<p>0<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>35<\/p>\n<\/td>\n<td>\n<p>12<\/p>\n<\/td>\n<td>\n<p>1<\/p>\n<\/td>\n<td>\n<p>12<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>45<\/p>\n<\/td>\n<td>\n<p>5<\/p>\n<\/td>\n<td>\n<p>2<\/p>\n<\/td>\n<td>\n<p>10<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>Total<\/strong><\/p>\n<\/td>\n<td>&nbsp;<\/td>\n<td>&nbsp;<\/td>\n<td>\n<p><strong>&Sigma;f_i u_i = 2<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Mean =&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"41\" src=\"https:\/\/app.kapdec.com\/questions-images\/4Qn17opoh0mV1765108302.gif?time=1765108303\" width=\"609\" \/><br \/>\nThis provides a third verification.<\/p>\n<p><strong>b) Find the median marks.<\/strong><br \/>\nTotal number of students, n = 50.,&nbsp;&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"35\" src=\"https:\/\/app.kapdec.com\/questions-images\/vty9TKAX91UL1765108303.gif?time=1765108303\" width=\"58\" \/>.<br \/>\nThe cumulative frequency just greater than or equal to 25 is 33. So, the median class is 20-30.<\/p>\n<ul>\n<li>l (lower limit) = 20<\/li>\n<li>cf (cumulative frequency of preceding class) = 15<\/li>\n<li>f (frequency of median class) = 18<\/li>\n<li>h (class width) = 10<\/li>\n<\/ul>\n<p>Median =&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"48\" src=\"https:\/\/app.kapdec.com\/questions-images\/0BgJguJyrkbP1765108303.gif?time=1765108304\" width=\"294\" \/><br \/>\n=&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"37\" src=\"https:\/\/app.kapdec.com\/questions-images\/xzIoMc5aqmGe1765108303.gif?time=1765108304\" width=\"432\" \/><\/p>\n<p>So, the median marks are approximately&nbsp;<strong>25.56<\/strong>.<\/p>\n<p><strong>c) Find the modal marks.<\/strong><br \/>\nThe class with the highest frequency is 20-30 (f=18). So, the modal class is 20-30.<\/p>\n<ul>\n<li>l = 20<\/li>\n<li>f_1 = 18<\/li>\n<li>f_0 = 10 (frequency of preceding class)<\/li>\n<li>f_2 = 12 (frequency of succeeding class)<\/li>\n<li>h = 10<\/li>\n<\/ul>\n<p>Mode =&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"41\" src=\"https:\/\/app.kapdec.com\/questions-images\/wYOMBqXXKw2W1765108303.gif?time=1765108304\" width=\"370\" \/><br \/>\n=&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"37\" src=\"https:\/\/app.kapdec.com\/questions-images\/LrBnuNxrlomg1765108303.gif?time=1765108304\" width=\"301\" \/><br \/>\n=&nbsp;<img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"37\" src=\"https:\/\/app.kapdec.com\/questions-images\/8iOxU97pI31A1765108304.gif?time=1765108304\" width=\"274\" \/><\/p>\n<p>So, the modal marks are approximately&nbsp;<strong>25.71<\/strong>.<\/p>\n<p><strong>d) Draw a histogram and frequency polygon.<\/strong><\/p>\n<p><strong>Histogram:<\/strong><\/p>\n<ul>\n<li>On the x-axis, take the class intervals (0-10, 10-20, etc.).<\/li>\n<li>On the y-axis, take the frequencies (5, 10, 18, etc.).<\/li>\n<li>Draw bars for each class interval with heights corresponding to their frequencies. Since class widths are equal, the bars will have proportional heights.<\/li>\n<\/ul>\n<p><strong>Frequency Polygon:<\/strong><\/p>\n<ul>\n<li>Find the class marks: 5, 15, 25, 35, 45.<\/li>\n<li>Plot points at (class mark, frequency): (5,5), (15,10), (25,18), (35,12), (45,5).<\/li>\n<li>Join these points with straight lines.<\/li>\n<li>To close the polygon, also plot points at the previous and next class marks with zero frequency: (-5,0) and (55,0), and connect them.<\/li>\n<\/ul>\n<p><strong>Final Answers:<\/strong><br \/>\na) Mean = 25.4<br \/>\nb) Median &asymp; 25.56<br \/>\nc) Mode &asymp; 25.71<br \/>\nd) Histogram and frequency polygon as described.<\/p>\n<p>The mean calculation is rigorously confirmed by three independent methods: Direct, Assumed Mean, and Step-Deviation.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Unit: Statistics and Probability Chapter: Mean, Mode, Median Graphical Representation of Frequency Distribution Reference: &#8211; Introduction to Statistics, Measures of Central Tendency, Mean (Arithmetic Mean), Median, Mode, Graphical Representation: Bar Graphs, Histograms, Frequency Polygons, Ogives (Cumulative Frequency Curves), Comparison and Application After studying this chapter, you should be able to understand: The concepts of mean, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[570],"tags":[],"class_list":["post-9140","post","type-post","status-publish","format-standard","hentry","category-math-sci-olympiad"],"_links":{"self":[{"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/posts\/9140","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/comments?post=9140"}],"version-history":[{"count":0,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/posts\/9140\/revisions"}],"wp:attachment":[{"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/media?parent=9140"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/categories?post=9140"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kapdec.com\/help\/wp-json\/wp\/v2\/tags?post=9140"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}