Selina solutions for Concise Mathematics [English] Class 9 ICSE chapter 17 - Statistics [Latest edition]

Which of the following variables are discrete?

The marks obtained by 15 students in a test (out of hundred) are given below:

81, 72, 90, 90, 80, 55, 72, 66, 69, 80, 36. 54, 62, 56 and 58

The range of data is:

The class-mark of the class 35-45 is ______.

In the class-intervals 1-10, 11-20, 21-30: the class 11-20 after adjustment is ______.

The class marks of a frequency distribution are 10, 15, 20, 25,... The class corresponding to the class mark 15 is ______.

State, the following variable is continuous or discrete:
number of children in your class.

State, the following variable is continuous or discrete:
Distance travelled by car.

State, the following variable is continuous or discrete:
Sizes of shoes.

State, the following variable is continuous or discrete: Time.

State, the following variable is continuous or discrete: Number of patients in a hospital.

Given below are the marks obtained by 30 students in an examination:

Taking class intervals 1-10, 11-20, ....., 41-50; make a frequency table for the above distribution.

The marks of 24 candidates in the subject mathematics are given below:

The maximum marks are 50. Make a frequency distribution taking class intervals 0 - 10, 10-20, .......

Fill in the blank :
 A quantity which can very from one individual to another is called a ............. 

Fill in the blank :
Sizes of shoes are ........... variables.

Fill in the blank :
Daily temperatures is ........... variable.

Fill in the blank :
The range of data 7, 13, 6, 25, 18, 20, 16 is ............

Fill in the blank : 
In the class interval 35 - 46; the lower limit is .......... and the upper limit is .........

Fill in the blank :
The class mark of class interval 22 - 29 is ...........

Find the actual lower class limits, upper-class limits and the mid-values of the classes:

10 - 19, 20 - 29, 30 - 39 and 40 - 49.

Find the actual lower and upper-class limits and also the class marks of the classes:
1.1 - 2.0, 2.1 -3.0 and 3.1 - 4.0.

Use the table given below to find:
(a) The actual class limits of the fourth class.
(b) The class boundaries of the sixth class.
(c) The class mark of the third class.
(d) The upper and lower limits of the fifth class.
(e) The size of the third class.

Construct a cumulative frequency distribution table from the frequency table given below:

Construct a cumulative frequency distribution table from the frequency table given below:

Construct a frequency distribution table from the following cumulative frequency distribution:

Construct a frequency distribution table from the following cumulative frequency distribution:

Construct a frequency polygon for the following distribution:

Construct a combined histogram and frequency polygon for the following frequency distribution:

Construct a frequency polygon for the following data:

The daily wages in a factory are distributed as follows:

Draw a frequency polygon for this distribution.

The class-mark of class 19-30 is ______.

In a frequency distribution, the mid-value of a class is 10 and the width of the class is 6. The lower limit of the class is ______.

Statement (1): Let m be the mid-value and x be the upper limit of a class in a continuous frequency distribution, then lower limit of this class is 2m − x.

Statement (2): For a given class: `"lower limit + upper limit"/2` = mid-value of the class.

Assertion (A): 30 children were asked about the number of hours they watched TV programme every day. The results are recorded as under.

Then the number of children who watched TV for 10 or more hours a day is 22.

Reason (R): The assertion is not correct as the required number is 4 + 2 = 6.

Construct a frequency table from the following data:

Construct the frequency distribution table from the following cumulative frequency table:

(i) State the number of students in the age group 10 - 13.
(ii) State the age-group which has the least number of students.

Fill in the blank in the following table:

The value of π up to 50 decimal place is
3.14159265358979323846264338327950288419716939937510
(i) Make a frequency distribution table of digits from 0 to 9 after the decimal place.
(ii) Which are the most and least occurring digits?

Draw frequency polygons for each of the following frequency distribution: 

(a) using histogram

(b) without using histogram

Draw frequency polygons for each of the following frequency distribution:
(a) using histogram
(b) without using histogram

Using the class intervals 0-9, 10-19, 20-29,..., construct the frequency distribution for: 15, 8, 12, 7, 13, 16, 22, 29, 35, 49, 37 and 48.

Construct the cumulative frequency table for:

Construct a combined histogram and frequency polygon for the following frequency distribution:

Srikanth is a class IX Mathematics teacher in Chennai. After a class test, he asks a student to record the marks that all the students obtained. Narayanan scored the least marks 6 in the class and Keerthana scored the highest marks 59 in the class out of 60 marks. He prepares a frequency distribution table using the collected data and draws a histogram as shown below:

1. What is the width of each class?
2. What is the total number of students in class IX?
3. How many students scored 50% and above marks?
4. What is the range of the collected data?