NCERT Solutions Class 11 Mathematics Chapter 15 Statistics Download In Pdf

Chapter 15 Statistics Download in pdf

**Find the mean deviation about the mean for the data in Exercises 1 and 2.**

**Question 1.** 4, 7, 8, 9, 10, 12, 13, 17

**Question 2.** 38, 70, 48, 40, 42, 55, 63, 46, 54, 44

Find the mean deviation about the median for the data in Exercises 3 and 4.

**Question 3.** 13, 17, 16, 14, 11, 13, 10, 16, 11, 18, 12, 17

**Question 4. **36, 72, 46, 42, 60, 45, 53, 46, 51, 49

**Find the mean deviation about the mean for the data in Exercises 5 and 6.**

**Question 5.** xi 5 10 15 20 25 f i 7 4 6 3 5

**Question 6.** xi 10 30 50 70 90 f i 4 24 28 16 8

Find the mean deviation about the median for the data in Exercises 7 and 8.

**Question 7.** xi 5 7 9 10 12 15 f i 8 6 2 2 2 6

**Question 8.** xi 15 21 27 30 35
f i 3 5 6 7 8

**Find the mean deviation about the mean for the data in Exercises 9 and 10.**

**Question 9.** Income 0-100 100-200 200-300 300-400 400-500 500-600 600-700 700-800

per day
Number 4 8 9 10 7 5 4 3

of persons

**Question 10.** Height 95-105 105-115 115-125 125-135 135-145 145-155

in cms

Number of 9 13 26 30 12 10

boys

**Question 11.** Find the mean deviation about median for the following data :

Marks 0-10 10-20 20-30 30-40 40-50 50-60

Number of 6 8 14 16 4 2

Girls

**Question 12.** Calculate the mean deviation about median age for the age distribution of 100
persons given below:

Age 16-20 21-25 26-30 31-35 36-40 41-45 46-50 51-55

Number 5 6 12 14 26 12 16 9

Find the mean and variance for each of the data in Exercies 1 to 5.

**Question 1.** 6, 7, 10, 12, 13, 4, 8, 12

**Question 2. **First n natural numbers

**Question 3.** First 10 multiples of 3

**Question 4.** xi 6 10 14 18 24 28 30
fi 2 4 7 12 8 4 3

**Question 5.** xi 92 93 97 98 102 104 109 f i 3 2 3 2 6 3 3

**Question 6.** Find the mean and standard deviation using short-cut method.

xi 60 61 62 63 64 65 66 67 68

f i 2 1 12 29 25 12 10 4 5

**Find the mean and variance for the following frequency distributions in Exercises
7 and 8. **

**Question 7.** Classes 0-30 30-60 60-90 90-120 120-150 150-180 180-210

Frequencies 2 3 5 10 3 5 2

**Question 8.** Classes 0-10 10-20 20-30 30-40 40-50

Frequencies 5 8 15 16 6

**Question 9.** Find the mean, variance and standard deviation using short-cut method

Height 70-75 75-80 80-85 85-90 90-95 95-100 100-105105-110 110-115

in cms
No. of 3 4 7 7 15 9 6 6 3

children

**Question 10.** The diameters of circles (in mm) drawn in a design are given below:

Diameters 33-36 37-40 41-44 45-48 49-52
No. of circles 15 17 21 22 25
Calculate the standard deviation and mean diameter of the circles.[ Hint First make the data continuous by making the classes as 32.5-36.5, 36.5-40.5,
40.5-44.5, 44.5 - 48.5, 48.5 - 52.5 and then proceed.]

EXERCISE 15.3

**Question 1.** From the data given below state which group is more variable, A or B?

Marks 10-20 20-30 30-40 40-50 50-60 60-70 70-80

Group A 9 17 32 33 40 10 9

Group B 10 20 30 25 43 15 7

**Question 2.** From the prices of shares X and Y below, find out which is more stable in value:

X 35 54 52 53 56 58 52 50 51 49

Y 108 107 105 105 106 107 104 103 104 101

**Question 3.** An analysis of monthly wages paid to workers in two firms A and B, belonging to
the same industry, gives the following results:
Firm A
Firm B
No. of wage earners 586 648
Mean of monthly wages Rs 5253 Rs 5253
Variance of the distribution 100 121
of wages

(i) Which firm A or B pays larger amount as monthly wages?

(ii) Which firm, A or B, shows greater variability in individual wages?

**Question 4.** The following is the record of goals scored by team A in a football session:

No. of goals scored 0 1 2 3 4

No. of matches 1 9 7 5 3

For the team B, mean number of goals scored per match was 2 with a standard
deviation 1.25 goals. Find which team may be considered more consistent?

**Question 5.** The sum and sum of squares corresponding to length x (in cm) and weight y
(in gm) of 50 plant products are given below:
50
1
i 212
i
x
=
Σ = ,
50
2
1
i 902 8
i
x .
=
Σ = ,
50
1
i 261
i
y
=
Σ = ,
50
2
1
i 1457 6
i
y .
=
Σ =
Which is more varying, the length or weight?

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- Chapter 1 Sets
- chapter 2 Relations And Functions
- Chapter 3 Trigonometric Functions
- Chapter 4 Principle of Mathematical Induction
- Chapter 5 Complex Numbers and Quadratic Equations
- Chapter 6 Linear Inequalities
- Chapter 7 Permutations And Combinations
- Chapter 8 Binomial Theorem
- Chapter 9 Sequences And Series
- Chapter 10 Straight Lines
- Chapter 11 Conic Sections
- Chapter 12 Introduction To Three Dimensional Geometry
- Chapter 13 Limits and Derivatives
- Chapter 14 Mathematical Reasoning
- Chapter 15 Statistics
- Chapter 16 Probability

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