Page 255 - ICSE Math 8

Example 1: Given below are marks obtained by 20 students of class VIII in Mathematics out of 25. Prepare
a discrete frequency distribution.
22, 15, 16, 16, 18, 20, 20, 20, 22, 16, 15, 18, 23, 22, 20, 22, 20, 23, 22, 20
Solution: Frequency Distribution of Marks of 20 Students
Marks Tally marks Frequency
15 | | 2
16 | | | 3
18 | | 2
20 | 6
22 5
23 | | 2
Total 20

EXERCISE 23.1

1. A survey was conducted in 25 families of a locality. Given below are the number of children in these
families.
2, 2, 3, 1, 1, 1, 2, 2, 3, 2, 2, 2, 1, 1, 1, 1, 2, 2, 3, 1, 2, 2, 1, 2, 2
Prepare a frequency distribution of the data.
2. Following are the marks of 35 students in an examination.
20, 16, 19, 25, 30, 20, 20, 19, 25, 25, 16, 30, 30, 28, 12, 5, 21, 23, 28, 24, 10, 8, 17, 22, 20, 23, 29, 15,
10, 10, 14, 25, 21, 11, 2
(a) Arrange the following data in ascending order.
(b) What are the highest marks scored?
(c) What are the lowest marks scored?
(d) Find the range of the above data.
(e) If 12 are the passing marks, how many students passed in the class?
(f) How many students scored above 25 marks?
3. The ages of 25 patients who visited a dentist are given below.
34, 35, 39, 38, 4, 9, 15, 26, 12, 13, 25, 32, 3, 12, 39, 14, 12, 12, 24, 8, 21, 16, 5, 12, 30
Prepare a frequency distribution of the data.
(a) What is the age of the youngest patient?
(b) What is the age of patients who visited the dentist maximum number of times?
(c) How many patients are above 30 years of age?
4. Given below are the heights of 15 students (in cm) of class VIII of a school.
128, 130, 125, 148, 142, 130, 130, 125, 128, 130, 148, 125, 142, 130, 130
Prepare a discrete frequency distribution.
5. A die was thrown 20 times and given below are the scores.
2, 3, 1, 2, 4, 6, 5, 2, 3, 1, 4, 3, 6, 6, 1, 1, 2, 4, 5, 2
Prepare a discrete frequency distribution.
6. The rainfall (in mm) in a city on 7 days of a certain week was recorded as follows:

Day Mon Tue Wed Thu Fri Sat Sun
Rainfall (in mm) 2.2 21.3 25.6 0.0 4.9 0.0 5.5
(a) Find the range of rainfall in the above data.

(b) On how many days was there no rainfall?

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