NCERT Exemplar Solutions Class 9 Mathematics Solutions for Statistics and Probability - Exercise 14.1 in Chapter 14 - Statistics and Probability

Question 9 Statistics and Probability - Exercise 14.1

A grouped frequency distribution table with classes of equal sizes using 63-72 (72 included) as one of the class is constructed for the following data:

30, 32, 45, 54, 74, 78, 108, 112, 66, 76, 88,

40, 14, 20, 15, 35, 44, 66, 75, 84, 95, 96,

102, 110, 88, 74, 112, 14, 34, 44.

The number of classes in the distribution will be :

(A) 9

(B) 10

(C) 11

(D) 12


(B) 10


According to the question,

The given frequency varies from 14 to 112.

So the class intervals are as follows:

13-22, 23-32, 33-42, 43-52, 53-62, 63-72, 73-82, 83-92, 93-102, 103-112.

Number of class interval = 10.

Hence, option (B) is the correct answer.

Video transcript
"hello students welcome to the lead our solving session and in today's video session we are going to solve one more question related to frequency distribution all right so i'm going to read the question first a grouped frequency distribution table with classes of equal size using 63 to 72 okay we are going to include 72 as well right so 72 included as one of the class is constructed for the following data right so the data is given here all right so we have to find out okay the number of the classes in the distribution okay so how many classes will be there for the given data all right so now let's solve this question okay so okay if you carefully observe the data so okay we'll see that okay so basically if you check the data so according to a given data given data okay frequency frequency okay frequency varies from okay 14 to 112 right okay so frequency is varying from 14 to 120 right okay and okay one of the data is given here okay one um okay interval is given here right so okay that interval is okay class one class interval is given here okay so class interval okay given class interval that is 63 272 right okay that means okay size of the each class size will be 72 minus 63 okay which is equals to 9 right that means in each class interval nine um observations will be there all right okay so that's why okay the class interval the class interval class intervals okay we can construct as follows okay so the first is first interval will be 13 to 22 all right now next is 23 to 32 okay with the size of 9 then 33 to 42 then 43 to 52 then 53 to 62 okay then 63 272 and 73 to 82 the next class will be 83 to 92 then 93 to 102 okay and the last class will be 103 to 112 right that means okay total classes total classes okay will be 10 all right okay and that's why option b is correct answer all right so that's all about today's session if you have any doubt please leave the comment below and please subscribe to this channel thanks for watching the video bye "
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