Chapter 32 Statistics - RD Sharma Solutions for Class 11-science Mathematics CBSE

Chapter 32 - Statistics Exercise Ex. 32.1

Question 1

Solution 1

Question 2

Solution 2

Question 3

Solution 3

Question 4

Solution 4

Question 5

Solution 5

Question 6

Solution 6

Question 7

Solution 7

Question 8

Solution 8

Question 9

Solution 9

Question 10

Calculate the mean deviation about the mean of the following data:

(v) 57, 64, 43, 67, 49, 59, 44, 47, 61, 59

Solution 10

Question 11

Solution 11

Question 12

Solution 12

Question 13

Solution 13

Question 14

Solution 14

Question 15

Solution 15

Question 16

Calculate the mean deviation on the following income groups of five and seven members from their medians:

I Income in Rs.	II income in Rs.
4000	3800
4200	4000
4400	4200
4600	4400
4800	4600
	4800
	5800

Solution 16

Note: Answer given in the book is incorrect.

Chapter 32 - Statistics Exercise Ex. 32.2

Question 1

Solution 1

Question 2

Solution 2

Question 3

Solution 3

Question 4

Solution 4

Question 5

Solution 5

Question 6

Solution 6

Question 7

Solution 7

Question 8

Solution 8

Question 9

Solution 9

Question 10

Find the mean deviation from the mean for the following data:

Size:	1 3 5 7 9 11 13 15
Frequency:	3 3 4 14 7 4 3 4

Solution 10

Question 11

Find the mean deviation from the median for the following data:

x_i	15 21 27 30
f_i	3 5 6 7

Solution 11

Note: Answer given in the book is incorrect.

Chapter 32 - Statistics Exercise Ex. 32.3

Question 1

Solution 1

Question 2

Solution 2

Question 3

Solution 3

Question 4

Solution 4

Question 5

Solution 5

Question 6

Solution 6

Question 7

Solution 7

Question 8

Solution 8

Question 9

Solution 9

Question 10

Calculate 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	45-50	50-55
Number of persons	5	6	12	14	26	12	16	9

Solution 10

Chapter 32 - Statistics Exercise Ex. 32.4

Question 1

Solution 1

Question 2

Find the mean, variance and standard deviation for the data:

6, 7, 10, 12, 13, 4, 8, 12.

Solution 2

Question 3

Solution 3

Question 4

Solution 4

Question 5

Solution 5

Question 6

Solution 6

Question 7

Solution 7

Question 8

Solution 8

Question 9

Solution 9

Question 10

Solution 10

Question 11

Solution 11

Question 12

Solution 12

Question 13

Solution 13

Question 14

Show that the two formulae for the standard deviation of ungrouped data

Solution 14

Chapter 32 - Statistics Exercise Ex. 32.5

Question 1

Solution 1

Question 2

Solution 2

Question 3

$F i n d space t h e space m e a n comma space a n d space t h e space s tan d a r d space d e v i a t i o n space f o r space t h e space f o l l o w i n g space d a t a :$

(i)

(ii)

Solution 3

Question 4

(ii)

Solution 4

Chapter 32 - Statistics Exercise Ex. 32.6

Question 1

Solution 1

Question 2

Solution 2

Question 3

Solution 3

Question 4

Solution 4

Question 5

Calculate the Mean, median and Standard Deviation of the following distribution:

Solution 5

Question 6

Solution 6

Question 7

Mean and standard deviation of 100 observation were found to be 40 and 10 respectively. If at the time of calculation two observations were wrongly taken as 30 and 70 in place of 3 and 27 respectively, find the correct standard deviation.

Solution 7

Question 8

While calculating the mean and variance of 10 readings , a student wrongly used the reading of 52 for the correct reading 25. He obtained the mean and variance as 45 and 16 respectively. Find the correct mean and the variance.

Solution 8

Question 9

Find the mean and variance of frequency distribution given below:

x_i:	1x <3	3 x<5	5x<7	7x<9
F_i:	6	4	5	1

Solution 9

Note: Answer given in the book is incorrect.

Question 10

Calculate mean, variance and standard deviation of the following frequency distribution:

Class:	0-10	10-20	20-30	30-40	40-50	50-60
Frequency:	11	29	18	4	5	3

Solution 10

Chapter 32 - Statistics Exercise Ex. 32.7

Question 1

Solution 1

We observe that the average monthly wages in both firms is same i.e. Rs. 2500. Therefore the plant with greater variance will have greater variability. Thus plant B has greater variability in individual wages.

Question 2

Solution 2

Question 3

Solution 3

Question 4

Solution 4

Question 5

Solution 5

Question 6

Solution 6

Question 7

Solution 7

Question 8

Solution 8

Question 9

Solution 9

Question 10

Solution 10

Question 11

Life of bulbs product by two factories A and B are given below:

Length of life

(in hours):

Factory A:

550-650 650-750 750-850 850-950 950-1050

(Number of bulbs)

Factor B:

10 22 52 20 16

(Number of bulbs)

8 60 24 15 12

The bulbs of which factory are more consistent from the point of view of length of life?

Solution 11

Question 12

Following are mark obtained, out of 100, by two students Ravi and Hashina in 10 tests:

Ravi:	25 50 45 30 70 42 36 48 35 60
Hashina:	10 70 50 20 95 55 42 60 48 80

Who is more intelligent and who is more consistent?

Solution 12

Chapter 32 - Statistics Exercise Ex. 32VSAQ

Question 1

Solution 1

Question 2

Solution 2

Question 3

Solution 3

Question 4

Solution 4

$W e space k n o w space t h a t space i f space y subscript i equals a x subscript i plus b comma space t h e n space v a r left parenthesis Y right parenthesis equals a squared left square bracket v a r left parenthesis X right parenthesis right square bracket H e r e comma space Y equals fraction numerator a X plus b over denominator c end fraction equals a over c X plus b over c T h e r e f o r e comma space v a r left parenthesis Y right parenthesis equals space a squared over c squared left square bracket v a r left parenthesis X right parenthesis right square bracket equals fraction numerator a squared sigma squared over denominator c squared end fraction S. D. equals open vertical bar a over c close vertical bar sigma$