Chapter 32 Statistics Exercise Ex. 32.1

Question 1(i)

Solution 1(i)

Question 1(ii)

Solution 1(ii)

Question 1(iii)

Solution 1(iii)

Question 1(iv)

Solution 1(iv)

Question 1(v)

Solution 1(v)

Question 2(i)

Solution 2(i)

Question 2(ii)

Solution 2(ii)

Question 2(iii)

Solution 2(iii)

Question 2(iv)

Solution 2(iv)

Question 2(v)

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

(v) 57, 64, 43, 67, 49, 59, 44, 47, 61, 59Solution 2(v)

Question 4

Solution 4

Question 5(i)

Solution 5(i)

Question 5(ii)

Solution 5(ii)

Question 5(iii)

Solution 5(iii)

Question 6

Solution 6

Question 3

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. 
40003800
42004000
44004200
46004400
48004600
 4800
 5800

Solution 3

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(i)

Solution 4(i)

Question 4(ii)

Solution 4(ii)

Question 4(iii)

Solution 4(iii)

Question 4(iv)

Solution 4(iv)

Question 5(ii)

Solution 5(ii)

Question 5(iii)

Solution 5(iii)

Question 4(v)

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 4(v)

Question 5(i)

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

xi15 21 27 30
fi 3 5 6 7

Solution 5(i)

Note: Answer given in the book is incorrect.

Chapter 32 Statistics Exercise Ex. 32.3

Question 1

Solution 1

Question 2(i)

Solution 2(i)

Question 2(ii)

Solution 2(ii)

Question 2(iii)

Solution 2(iii)

Question 3

Solution 3

Question 4

Solution 4

Question 5

Solution 5

Question 7

Solution 7

Question 8

Solution 8

Question 6

Calculate mean deviation about median age for the age distribution of 100 persons given below:

Age:16-2021-2526-3031-3536-4041-4545-5050-55
Number of persons5612142612169

Solution 6

Chapter 32 – Statistics Exercise Ex. 32.4

Question 1(i)

Solution 1(i)

Question 1(ii)

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

6, 7, 10, 12, 13, 4, 8, 12.Solution 1(ii)

Question 1(iii)

Solution 1(iii)

Question 1(iv)

Solution 1(iv)

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

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

Solution 11

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 7

Solution 7

Question 8

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 8

Question 9

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 9

Question 6

Find the mean and variance of frequency distribution given below:

xi:1 x <3 x<55 x<77 x<9
Fi:6451

Solution 6

Note: Answer given in the book is incorrect. Question 10

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

Class:0-1010-2020-3030-4040-5050-60
Frequency:112918453

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


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