Advertisements
Advertisements
प्रश्न
If the mean of the following distribution is 7.5, find the missing frequency ‘f’:
| Variable : | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Frequency: | 20 | 17 | f | 10 | 8 | 6 | 7 | 6 |
उत्तर
| Variable | Frequency `(f)` | `fx` |
| 5 | 20 | 100 |
| 6 | 17 | 102 |
| 7 | f | 7f |
| 8 | 10 | 80 |
| 9 | 8 | 72 |
| 10 | 6 | 60 |
| 11 | 7 | 77 |
| 12 | 6 | 72 |
| `sumf` = 74 + `f` | 563 + 7`f` |
∵ M = `(sumfx)/(sumf)`
∴ 7.5 = `(563 + 7f)/(74 + f)`
∴ 555 + 7.5f = 563 + 7f
∴ 0.5f = 8
∴ f = 16.
APPEARS IN
संबंधित प्रश्न
Candidates of four schools appear in a mathematics test. The data were as follows:-
| Schools | No. of Candidates | Average Score |
| I | 60 | 75 |
| II | 48 | 80 |
| III | NA | 55 |
| IV | 40 | 50 |
If the average score of the candidates of all the four schools is 66, find the number of candidates that appeared from school III.
The weekly observations on cost of living index in a certain city for the year 2004 - 2005 are given below. Compute the weekly cost of living index.
| Cost of living Index | Number of Students |
| 1400 - 1500 | 5 |
| 1500 - 1600 | 10 |
| 1600 - 1700 | 20 |
| 1700 - 1800 | 9 |
| 1800 - 1900 | 6 |
| 1900 - 2000 | 2 |
The following table shows the marks scored by 140 students in an examination of a certain paper:
| Marks: | 0 - 10 | 10 - 20 | 20 - 30 | 30 - 40 | 40 - 50 |
| Number of students: | 20 | 24 | 40 | 36 | 20 |
Calculate the average marks by using all the three methods: direct method, assumed mean deviation and shortcut method.
Find the mean of the following frequency distribution using step-deviation method
| Class | 0 – 10 | 10 – 20 | 20 – 30 | 30 – 40 | 40 – 50 |
| Frequency | 7 | 10 | 15 | 8 | 10 |
If the mean of first n natural numbers is \[\frac{5n}{9}\], then n =
A study of the yield of 150 tomato plants, resulted in the record:
| Tomatoes per Plant | 1 - 5 | 6 - 10 | 11 - 15 | 16 - 20 | 21 - 25 |
| Number of Plants | 20 | 50 | 46 | 22 | 12 |
Calculate the mean of the number of tomatoes per plant.
The average score of girls in class X examination in school is 67 and that of boys is 63. The average score for the whole class is 64.5. Find the percentage of girls and boys in the class.
In a small scale industry, salaries of employees are given in the following distribution table:
|
Salary (in Rs.) |
4000 - 5000 |
5000 - 6000 |
6000 - 7000 |
7000 - 8000 |
8000 - 9000 |
9000 - 10000 |
|
Number of employees |
20 | 60 | 100 | 50 | 80 | 90 |
Then the mean salary of the employee is?
The weights (in kg) of 50 wrestlers are recorded in the following table:
| Weight (in kg) | 100 – 110 | 110 – 120 | 120 – 130 | 130 – 140 | 140 – 150 |
| Number of wrestlers |
4 | 14 | 21 | 8 | 3 |
Find the mean weight of the wrestlers.
Find the mean of the following frequency distribution:
| Class: | 10 – 15 | 15 – 20 | 20 – 25 | 25 – 30 | 30 – 35 |
| Frequency: | 4 | 10 | 5 | 6 | 5 |
