NCERT Class 10 Chapter 14 Statistics CBSE Board Sample Problems Short Answer

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Question

If the mean of the following distribution is 54, find the missing frequency X:

Distribution is 54, find the missing frequency X

Class

0-20

20-40

40-60

60-80

80-100

Frequency

16

14

24

26

x

Solution

Distribution is 54, find the missing frequency X

Class Interval

0-20

20-40

40-60

60-80

80-100

10

30

50

70

90

16

14

24

26

x

160

420

1200

1820

90x

Total

80+x

3600+90x

Mean

Question

The following table shows the distribution of weights of 100 candidates appearing for a competition. Determine the modal weight.

Determine the modal weight

Weight (in kg)

50-55

55-60

60-65

65-70

70-75

75-80

No. of candidates

13

18

45

16

6

2

Solution

Determine the modal weight

Class Interval

50-55

55-60

60-65

65-70

70-75

75-80

13

18

45

16

6

2

Hear

Mode

Question

Sonic students of Class X donated for the welfare of old age persons. Their contributions are shown in the following frequency distribution:

Sonic students of Class X donated for the welfare of old age persons

Amount (in Rs)

0-20

20-40

40-60

60-80

80-100

No. of students

5

8

12

11

4

Find median and mode for their contribution.

Solution

Median

For mode modal class 40-60

Mode

Sonic students of Class X donated for the welfare of old age persons

Number of students

c.f.

0-20

20-40

40-60

60-80

80-100

5

8

12

11

4

5

13

25

36

40

Question

The average score of boys in the examination of a school is 71 and that of the girls is 73. The average score of the school in the examination is 71.8. Find the ratio of the number of boys to the number of girls who appeared in the examination.

Solution

Let number of boys in the school be x

Average score of boys = 71

Total score of boys in the examination of the school

Let number of girls in the school be y

Average score of girls = 73

Total score of girls in the examination of the school

Now, average score of the school in examination

Question

The following data gives the information on the observed life times (in hours) of 150 electrical components

The observed life times (in hours) of 150 electrical components

Life time (in hours )

0-20

20-40

40-60

60-80

80-100

0-20

20-40

Frequency

15

10

35

50

40

Solution

The observed life times (in hours) of 150 electrical components

Life time (in hours )

Frequency

0-20

20-40

40-60

60-80

80-100

15

10

35

50 Model Class

40

Model class is 60-80

Mode

Question

Determine the missing frequency x, from the following data when Mode is 67.

Determine the missing frequency x

Class

40-50

50-60

60-70

70-80

80-90

frequency

5

x

15

12

7

Solution

Determine the missing frequency x

Class interval

Frequency

40-50

50-60

60-70

70-80

80-90

5

Modal class

7

Mode =67 given

Model class is 60-70

Mode

Question

Find the unknown values in the following table:

Find the unknown values in the following table

Class interval

Frequency

Cumulative Frequency

0-10

10-20

20-30

30-40

40-50

5

7

5

5

18

30

Solution

Class interval Frequency Cumulative Frequency

Class interval

Frequency

Cumulative Frequency

0-10

10-20

20-30

30-40

40-50

5

7

5

5

18

30

From table:

Question

The mode of a distribution is 55 & the modal class is 45-60 and the frequency preceding the modal class is 5 and the frequency after the modal class is 10. Find the frequency of the modal class

Solution

Mode= 55

Modal class

Class preceding modal class

Class succeeding modal class

Mode

Question

Find the mean of 30 numbers given mean often of them is 12 and the mean of remaining 20 is 9.

Solution

Total number of mean = 30

Mean of 10 is = 12

Mean of 20 numbers is = 9

By (1) + (2)

Mean of 20 numbers =

10

Question

The mean of 5 numbers is 10. If 3 decrease each number, find the mean of the new number.

Solution

Mean of 5 nos

Since, each number is decreased by 3, then the sum is decreased by

Mean of new no

Question

The median of a data is 20. If each item is increased by 2, find the new median.

Solution

Median is the middle most item and each item is increased by 2, the new median will be

Question

The mean of 20 observations is 12. If each observation is increased by 5, then find the new mean.

Solution

If each observation is increased by 5 then the required new mean is also increased by 5.

Thus, the new mean is 17.

Question

The mean of 6, and Find the value of x

Solution

Mean

Question

Find the Mode of the following data:

Class Intervals 10 – 14 15 -19 20-24 25-29 30-34 35-39

Frequencies 30 45 75 35 25 10

Also, if the Median of the distribution is 20.8, find the Mean.

Solution

Modal class is

Mode

Using Empirical formula

3 median