Selina solutions concise maths class 9 icse Solutions for Chapter 18 chapter 18 statistics

Exercises in Chapter 18 chapter 18 statistics Grade 9

Exercise 18(A)

Exercise 18(B)

Questions in Exercise 18(A)

State, which of the following variables are continuous and which are discrete:

a) Number of children in your class

b) Distance traveled by car.

c) Size of shoes

d) Time

e) The number of patients in a hospital.

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

08 17 33 41 47 23 20 34

09 18 42 14 30 19 29 11

36 48 40 24 22 02 16 21

15 32 47 44 33 01

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

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.

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

Ages No.of Students

Below 4 0

Below 7 85

Below 10 140

Below 13 243

Below 16 300

(i) State the number of students in the age group 10-13.

(ii) State the age-group which has the least number of students.

The value of 𝝅 up to 50 decimal places is:

3.14159265358979323846264338327950288419716939937510

(i) Make a frequency distribution table of the digits from 0 to 0 after the decimal place.

(ii) Which are the most and the least occurring digits?

Questions in Exercise 18(B)

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

Class-intervals	10-20	20-30	30-40	40-50	50-60
Frequency	3	5	6	4	2

Construct a frequency polygon for the following data:

Class-intervals	10-14	15-19	20-24	25-29	30-34
Frequency	5	8	12	9	4

The daily wages in a factory are distributed as follows:

Daily Wages	125-175	175-225	225-275	275-325	325-375
No. of workers	4	20	22	10	6

Draw frequency polygons for each of the following frequency distribution;

(a) Using histogram

(b) Without using histogram

(i)

C.I	10-30	30-50	50-70	70-90	90-110	110-130	130-150
f	4	7	5	9	5	6	4

(ii)

C.I	5-15	15-25	25-35	35-45	45-55	55-65
f	8	16	18	14	8	2

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Chapters in this book

Chapter 1- Rational and Irrational Numbers

Chapter 2- Compound Interest [Without Using Formula

Chapter 3- Compound Interest [Using Formula

Chapter 4- Expansions

Chapter 5- Factorisation

Chapter 6- Simultaneous Equations

Chapter 7- Indices [exponents]

Chapter 8- Logarithms

Chapter 9- Triangles [Congruency in Triangles]

Chapter 10- Isosceles Triangle

Chapter 11- Inequalities

Chapter 12- Mid-Point and Its Converse

Chapter 13- Pythagoras Theorem

Chapter 14- Rectilinear Figures

Chapter 15- Construction of Polygons

Chapter 16- Area Theorems

Chapter 17- Circles

Chapter 18- Statistics

Chapter 19- Mean and Median

Chapter 20- Area and Perimeter of Plane Figures

Chapter 21- Solids

Chapter 22- Trigonometrical Ratios

Chapter 23- Trigonometrical Ratios of Standard Angles

Chapter 24- Solution Of Right Triangles

Chapter 25- Complementary angles

Chapter 26- Co-ordinate Geometry

Chapter 27- Graphical Solution

Chapter 28- Distance Formula