To find the mean, we divide the sum of the observations by the total number of observations. However, for grouped data, we cannot find the exact Mean, we can only give estimates. In statistics, Mean, Median and Mode are known as the measures of central tendency.

Mean = ∑X ÷ N The simple arithmetic mean considers all the values in data as equal and grants equal importance to each value. Whereas, in weighted arithmetic mean weights or importance is assigned to the values. Without further delay let us study methods of constructing mean.

L = Lower limit Mode of modal class. fm = Frequency of modal class. f1 = Frequency of class preceding the modal class. f2= Frequency of class succeeding the modal class….Mode Formula Calculator.

What are the 4 methods of finding mean​

In statistics the assumed mean is a method for calculating the arithmetic mean and standard deviation of a data set. It simplifies calculating accurate values by hand. Its interest today is chiefly historical but it can be used to quickly estimate these statistics.

To find the mean using direct method, for grouped data, multiply the mid – point of intervals (Xi) with the frequency (fi) of that interval and take their sum denoted by ∑Xifi. Now, divide this expression with the sum of frequencies, denoted by ∑fi.

The direct method is also known as natural method. It was developed as a reaction to the grammar translation method and is designed to take the learner into the domain of the target language in the most natural manner. The main objective is to impart a perfect command of a foreign language.

The mean is the average of the numbers. It is easy to calculate: add up all the numbers, then divide by how many numbers there are. In other words it is the sum divided by the count.

Find the class mark of class interval 50-60. Then, we will substitute the value in the formula, class – mark=Lower limit + upper limit2 to determine the class-mark of the class-interval.

Class frequency refers to the number of observations in each class; n represents the total number of observations in the entire data set. For the supermarket example, the total number of observations is 200. The relative frequency may be expressed as a proportion (fraction) of the total or as a percentage of the total.

The class mark is also known as the class midpoint is the particular point in the middle of the class interval. it is given by , where a= lower limit and b= upper limit. Therefore , the class size and class mark of class 15-20 is 5 and 17.5.

$ /Rightarrow $Class mark of 100-120 is 110. Now we have to find out the values of /[{f_1}/] and /[{f_2}/].

So, the lower limit of this class is 90 and the upper limit is 120. Hence, the class mark of the class 90-120 is 105. So, the correct answer is “Option B”.

100+150/2 which is 125……

95 is the correct answer.

Here, 100 is the lower limit and 110 is the upper limit of the interval. The class mark of thee interval is given by : So, the class mark of the interval is 105.

The average of the values of the class limits for a given class. A class mark is also called a midvalue or central value (Kenney and Keeping 1962, p. 14), and is commonly denoted . SEE ALSO: Class Interval, Class Limits.

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Class size is the average number of students per class, calculated by dividing the number of students enrolled by the number of classes.