Maths Class 10 Chapter 14: Statistics

# Maths Class 10 Chapter 14: Statistics

Important Formulas

1.      The mean for grouped data can be found by the following methods:

i.            Direct method: In direct method, we use the following formula:

ii.            Assumed mean method: In assumed mean method, we use the following formula:

iii.            Step deviation method: In this method, we use the following formula:

2.      The mode for grouped data can be found by the following formula:

where l = lower limit of modal class
h = size of the class interval
f1 = frequency of the modal class
f0 = frequency of the class preceding the modal class

f2 = frequency of the class succeeding the modal class

3.      The cumulative frequency of a class is the frequency obtained by adding the frequencies of all the classes preceding the given class.

4.      The median for grouped data is found by the following formula:

where l = lower limit of median class
n = number of observations
cf = cumulative frequency of class preceding the median class
f = frequency of median class

h = class size

5.      We can represent a cumulative frequency distribution graphically as a cumulative frequency curve, or an ogive of the less than type and of the more than type.

6.      The median of grouped data can be obtained graphically as the x-coordinate of the point of intersection of the two ogives, e.g., intersection of less than type and more than type ogive.