#### Chapters

## Chapter 7: Statistics

#### Balbharati solutions for Class 9 Chapter 7 Exercise Practice set 7.1 [Page 111]

The following table shows the number of Buses and Trucks in nearest lakh units. Draw percentage bar-diagram. (Approximate the percentages to the nearest integer)

Year | No. of Trucks | No. of Buses |

2005-2006 | 47 | 9 |

2007-2008 | 56 | 13 |

2008-2009 | 60 | 16 |

2009-2010 | 63 | 18 |

In the table given below, the information is given about roads. Using this draw sub-divided and percentage bardiagram (Approximate the percentages to the nearest integer)

Year | Permanent Roads ( Lakh km.) |
Temporary Roads ( Lakh km.) |

2000-2001 | 14 | 10 |

2001-2002 | 15 | 11 |

2003-2004 | 17 | 13 |

2007-2008 | 20 | 19 |

#### Balbharati solutions for Class 9 Chapter 7 Exercise Practice set 7.2 [Page 113]

Classify following information as primary or secondary data.

Information of attendance of every student collected by visiting every class in a school.

Classify following information as primary or secondary data.

The information of heights of students was gathered from school records and sent to the head office, as it was to be sent urgently.

Classify following information as primary or secondary data.

In the village Nandpur, the information collected from every house regarding students not attending school.

Classify following information as primary or secondary data

For science project, information of trees gathered by visiting a forest.

#### Balbharati solutions for Class 9 Chapter 7 Exercise Practice set 7.3 [Pages 118 - 119]

For class interval 20-25 write the lower class limit and the upper class limit.

Find the class-mark of the class 35-40.

If class mark is 10 and class width is 6 then find the class.

Complete the Following Table.

Classes (age) | Tally marks | Frequency (No. of students) |

12-13 | ............. | |

13-14 | ............. | |

14-15 | ............. | ............. |

15-16 | ............. | |

N = ∑ f = 35 |

The value of π upto 50 decimal places is given below :

3.14159265358979323846264338327950288419716939937510 From this information prepare an ungrouped frequency distribution table of digits appearing after the decimal point.

In the tables given below, class-mark and frequencies is given. Construct the frequency tables taking inclusive and exclusive classes.

Class width | Frequency |

5 | 3 |

15 | 9 |

25 | 15 |

35 | 13 |

In the tables given below, class-mark and frequencies is given. Construct the frequency tables taking inclusive and exclusive classes

Class width | Frequency |

22 | 6 |

24 | 7 |

26 | 13 |

28 | 4 |

16, 15, 7, 4.5, 8.5, 5.5, 5, 6.5, 6, 10, 12, 13, 4.5, 4.9, 16, 11, 9.2, 7.3, 11.4, 12.7, 13.9, 16, 5.5, 9.9, 8.4, 11.4, 13.1, 15, 4.8, 10, 7.5, 8.5, 6.5, 7.2, 4.5, 5.7, 16, 5.7, 6.9, 8.9, 9.2, 10.2, 12.3, 13.7, 14.5, 10

#### Balbharati solutions for Class 9 Chapter 7 Exercise Practice set 7.4 [Pages 121 - 122]

Complete the following cumulative freuqency table :

Class (Height in cm) |
Frequency (No. of students) |
Less than type frequency |

150 - 153 | 05 | 05 |

153 - 156 | 07 | 05 + ....... = ........ |

156 - 159 | 15 | ....... + 15 = ......... |

159 - 162 | 10 | ........ + ........ = 37 |

162 - 165 | 05 | 37 + 5 = 42 |

165 - 168 | 03 | ......... + ....... = 45 |

Total N = 45 |

Complete the following Cumulative Frequency Table :

Class (Monthly income in Rs.) |
Frequency (No. of individuals) |
More than or equal to type cumulative frequency |

1000 - 5000 | 45 | ............. |

5000 - 10000 | 19 | ............. |

10000 -15000 | 16 | ............. |

15000-20000 | 02 | ............. |

20000-25000 | 05 | ............. |

Total N=87 |

The data is given for 62 students in a certain class regarding their mathematics marks out of 100. Take the classes 0-10, 10-20.. and prepare frequency distribution table and cumulative frequency table more than or equal to type.

55, 60, 81, 90, 45, 65, 45, 52, 30, 85, 20, 10, 75, 95, 09, 20, 25, 39, 45, 50, 78, 70, 46, 64, 42, 58, 31, 82, 27, 11, 78, 97, 07, 22, 2 36, 35, 40, 75, 80, 47, 69, 48, 59, 32, 83, 23, 17, 77, 45, 05, 23, 37, 38, 35, 25, 46, 57, 68, 45, 47, 49.

The data is given for 62 students in a certain class regarding their mathematics marks out of 100. Take the classes 0-10, 10-20.. and

prepare less than type cumulative frequency table and answer the following questions.

55, 60, 81, 90, 45, 65, 45, 52, 30, 85, 20, 10, 75, 95, 09, 20, 25, 39, 45, 50, 78, 70, 46, 64, 42, 58, 31, 82, 27, 11, 78, 97, 07, 22, 2 36, 35, 40, 75, 80, 47, 69, 48, 59, 32, 83, 23, 17, 77, 45, 05, 23, 37, 38, 35, 25, 46, 57, 68, 45, 47, 49.

(i) How many students obtained less than 40 marks ?

(ii) How many students obtained less than 10 marks ?

(iii) How many students obtained less than 60 marks ?

(iv) Find the cumulative frequency of the class 50-60.

#### Balbharati solutions for Class 9 Chapter 7 Exercise Practice set 7.5 [Page 125]

Yield of soyabean per acre in quintal in Mukund's field for 7 years was 10, 7, 5, 3, 9, 6, 9. Find the mean of yield per acre.

Find the median of the observations, 59, 75, 68, 70, 74, 75, 80.

The marks (out of 100) obtained by 7 students in Mathematics' examination are given below. Find the mode for these marks.

99, 100, 95, 100, 100, 60, 90

60, 70, 90, 95, 50, 65, 70, 80, 85, 95.

Find the mean, median and mode of the data.

The calculated mean of 50 observations was 80. It was later discovered that observation 19 was recorded by mistake as 91. What was the correct mean?

*x*+ 1,

*x*+ 3, 14, 16, 19, 20

*x*

The mean of 35 observations is 20, out of which mean of first 18 observations is 15 and mean of last 18 observation is 25. Find the 18th observation.

The mean of 5 observations is 50. One of the observations was removed from the data, hence the mean became 45. Find the observation which was removed.

There are 40 students in a class, out of them 15 are boys. The mean of marks obtained by boys is 33 and that for girls is 35. Find out the mean of all students in the class.

Find the mode of the data

In the following table, the information is given about the number of families and the siblings in the families less than 14 years of age. Find the mode of the data

No. of siblings | 1 | 2 | 3 | 4 |

Families | 15 | 25 | 5 | 5 |

Find the mode of the following data.

Marks | 35 | 36 | 37 | 38 | 39 | 40 |

No of Student | 09 | 07 | 09 | 04 | 04 | 02 |

#### Balbharati solutions for Class 9 Chapter 7 Exercise Problem Set 7 [Pages 126 - 217]

Which of the following data is not primary ?

(A) By visiting a certain class, gathering information about attendence of students.

(B) By actual visit to homes, to find number of family members.

(C) To get information regarding plantation of soyabean done by each farmer

from the village Talathi.

(D) Review the cleanliness status of canals by actually visitiing them.

What is the upper class limit for the class 25-35 ?

25

35

60

30

What is the class-mark of class 25-35 ?

25

35

60

30

If the classes are 0-10, 10-20, 20-30... then in which class should the observation 10 be included ?

0 - 10

10 - 20

0 - 10 and 10 - 20 in these 2 classes

20 - 30

If `barX` is the mean of `X_1`, `X_2` ...............`X_n` and ` bar Y` is the mean of `Y_1`, `Y_2`....................` Y_n` and `barZ` is the mean `X_1`, `X_2`.............. `X_n`, `Y_1`, `Y_2`, .........................`Y_n` then Z ?

`(bar X + bar Y) / 2`

`bar X + bar Y`

`(bar X + bar Y) / n`

` (barX + bar Y) /(2n)`

The mean of five numbers is 80, out of which mean of 4 numbers is 46, find the 5th number

4

20

434

66

None of the above

Mean of 100 observations is 40. The 9th observation is 30. If this is replaced by 70 keeping all other observations same, find the new mean.

40.6

40.4

40.3

40.7

What is the the mode of 19, 19, 15, 20, 25, 15, 20, 15?

15

20

19

25

What is the median of 7, 10, 7, 5, 9, 10 ?

7

9

8

10

From following table, what is the cumulative frequency of less than type for the class 30-40 ?

Class | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 |

Frequency | 7 | 3 | 12 | 13 | 2 |

13

15

35

22

The mean salary of 20 workers is Rs.10,250. If the salary of office superintendent is added, the mean will increase by Rs.750. Find the salary of the office superintendent.

The mean of nine numbers is 77. If one more number is added to it then the mean increases by 5. Find the number added in the data.

The monthly maximum temperature of a city is given in degree celcius in the following data. By taking suitable classes, prepare the grouped frequency distribution table

29.2, 29.0, 28.1, 28.5, 32.9, 29.2, 34.2, 36.8, 32.0, 31.0, 30.5, 30.0, 33, 32.5, 35.5, 34.0, 32.9, 31.5, 30.3, 31.4, 30.3, 34.7, 35.0, 32.5, 33.5, 29.0, 29.5, 29.9, 33.2, 30.2

From the table, answer the following questions.

(i) For how many days the maximum temperature was less than 34^{o}C ?

(ii) For how many days the maximum temperature was 34^{o}C or more than 34^{o}C ?

If the mean of the following data is 20.2, then find the value of *p*.

`x_i` | 10 | 15 | 20 | 25 | 30 |

`f_i` | 6 | 8 | p | 10 | 6 |

There are 68 students of 9th standard from model Highschool, Nandpur. They have scored following marks out of 80, in written exam of mathematics.

70, 50, 60, 66, 45, 46, 38, 30, 40, 47, 56, 68, 80, 79, 39, 43, 57, 61, 51, 32, 42, 43, 75, 43, 36, 37, 61, 71, 32, 40, 45, 32, 36, 42, 43, 55, 56, 62, 66, 72, 73, 78, 36, 46, 47, 52, 68, 78, 80, 49, 59, 69, 65, 35, 46, 56, 57, 60, 36, 37, 45, 42, 70, 37, 45, 66, 56, 47

By taking classes 30-40, 40-50, .... prepare the less than type cumulative frequency table

## Chapter 7: Statistics

## Balbharati solutions for Class 9 Algebra chapter 7 - Statistics

Balbharati solutions for Class 9 chapter 7 (Statistics) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the Maharashtra State Board Balbharati Class 9 Mathematics 1 Algebra solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 9 Algebra chapter 7 Statistics are Introduction of Statistics, Bar Diagrams, Collection of Data, Frequency Distribution Table, Measures of Central Tendency, Cumulative Frequency Table.

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