Q7 of 26 Page 14

The blood groups of 30 students of class VIII are recoded as follows:

A, B, O, O, AB, O, A, O, B, A, O, B, A, O, O, A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O


Represent this data in the form of a frequency distribution table. Find out which is the most common and which is the rarest blood group among these students.

To Find: Frequency distribution table and most common and rarest blood group

Given: Blood groups of 30 students


Concept Used:


The frequency of observation is the number of times that observation occurs.


Explanation:


Frequency distribution table will be:



From the table,


Most common blood group = Blood group with maximum frequency


Most common blood group is O with a frequency of 12.


Rarest blood group = Blood group with minimum frequency


Rarest blood group is AB with a frequency of 3.


More from this chapter

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5

Let l be the lower-class limit of a class-interval in a frequency distribution and m be the mid-point of the class. Then, find the upper-class limit f.

 6

In a group of 10 students, marks obtained in a subject are as follows: 23, 22, 45, 38, 49, 23, 45, 10, 45, 39. Find the following:
(i) Mean marks of class
(ii) Median marks of class
(iii) Modal marks of class

 8

Thirty children were asked about the number of hours they watched T.V. programmes in the previous week. The results were found as follows:

1, 6, 2, 3, 5, 12, 5, 8, 4, 8, 10, 3, 4, 12, 2, 8, 15, 1, 17, 6, 3, 2, 8, 5, 9, 6, 8, 7, 14, 12


(i) Make a grouped frequency distribution table for this data, taking class width 5 and one of the class intervals as 5-10.


(ii) How many children watched television for 15 or more hours a week?

 9

Find out the mode of the following marks obtained by 15 students in a class:

Marks: 4, 6, 5, 7, 9, 8, 10, 4, 7, 6, 5, 9, 8, 7, 7.