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प्रश्न
Construct a frequency polygon for the following distribution:
| Class-intervals | 0-4 | 4 - 8 | 8 - 12 | 12 - 16 | 16 - 20 | 20 - 24 |
| Frequency | 4 | 7 | 10 | 15 | 11 | 6 |
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उत्तर
The frequency polygon is shown in the following figure
Steps:
(i) Drawing a histogram for the given data.
(ii) Marking the mid-point at the top of each rectangle of the histogram drawn.
(iii) Also, marking mid-point of the immediately lower class-interval and mid-point of the immediately higher class-interval.
(iv) Joining the consecutive mid-points marked by straight lines to obtain the required frequency polygon.
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संबंधित प्रश्न
The following table gives the life times of 400 neon lamps:-
| Life time (in hours) | Number of lamps |
| 300 - 400 | 14 |
| 400 - 500 | 56 |
| 500 - 600 | 60 |
| 600 - 700 | 86 |
| 700 - 800 | 74 |
| 800 - 900 | 62 |
| 900 - 1000 | 48 |
- Represent the given information with the help of a histogram.
- How many lamps have a life time of more than 700 hours?
100 surnames were randomly picked up from a local telephone directory and a frequency distribution of the number of letters in the English alphabet in the surnames was found as follows:
| Number of letters | Number of surnames |
| 1 - 4 | 6 |
| 4 - 6 | 30 |
| 6 - 8 | 44 |
| 8 - 12 | 16 |
| 12 - 20 | 4 |
- Draw a histogram to depict the given information.
- Write the class interval in which the maximum number of surnames lie.
Given below (Fig. below) is the bar graph indicating the marks obtained out of 50 in mathematics paper by 100 students. Read the bar graph and answer the following questions:
(i) It is decided to distribute work books on mathematics to the students obtaining less than 20 marks, giving one workbook to each of such students. If a work book
costs Rs 5, what sum is required to buy the work books?
(ii) Every student belonging to the highest mark group is entitled to get a prize of Rs. 10. How much amount of money is required for distributing the prize money?
(iii) Every student belonging to the lowest mark—group has to solve 5 problems per day. How many problems, in all, will be solved by the students of this group per day?
(iv) State whether true or false.
a. 17% students have obtained marks ranging from 40 to 49.
b. 59 students have obtained marks ranging from 10 to 29.
(v) What is the number of students getting less than 20 marks?
(vi) What is the number of students getting more than 29 marks?
(vii) What is the number of students getting marks between 9 and 40?
(viii) What is the number of students belonging to the highest mark group?
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Explain the reading and interpretation of bar graphs.
The following bar graph shows the results of an annual examination in a secondary school. Read the bar graph and choose the correct alternative in each of the following:
(i) The pair of classes in which the results of boys and girls are inversely proportional are:
(a) VI, VIII (b) VI, IX (c) VIII, IX (d) VIII, X
(ii) The class having the lowest failure rate of girls is
(a) VII (b) X (c) IX (d) VIII
(iii)The class having the lowest pass rate of students is
(a) VI (b) VII (c) VIII (d) IX
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| Day | Mon | Tue | Wed | Thurs | Fri | Sat | Sun |
| Number of T.V. Sets | 300 | 400 | 150 | 250 | 100 | 350 | 200 |
Represent the above information by a pictograph .
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| Year | 1992 | 1993 | 1994 | 1995 | 1996 |
| Loan (in crores of rupees) |
28 | 33 | 55 | 55 | 80 |
(i) Represent the above data with the help of a bar graph.
(ii) With the help of the bar graph, indicate the year in which amount of loan is not increased over that of the preceding year.
The following data gives the demand estimates of the Government of India, Department of Electronics for the personnel in the Computer sector during the Eighth Plan period (1990-95):
| Qualifications: | MCA (Master in Computer applications) |
DCA (Diploma in Computer Applications) |
DCE (Diploma in Computer Engineering) |
CL (Certificate Level Course) |
ST (Short-term Course) |
| Personnel Required | 40600 | 181600 | 18600 | 670600 | 1802900 |
Represent the data with the help of a bar graph. Indicate with the help of the bar graph the course where estimated requirement is least.
Construct a histogram for the following data:
| Monthly School fee (in Rs): |
30-60 | 60-90 | 90-120 | 120-150 | 150-180 | 180-210 | 210-240 |
| No of Schools | 5 | 12 | 14 | 18 | 10 | 9 | 4 |
A frequency polygon is constructed by plotting frequency of the class interval and the
