Advertisements
Advertisements
प्रश्न
The following table gives the marks scored by a set of students in an examination. Calculate the mean of the distribution by using the short cut method.
| Marks | Number of Students (f) |
| 0 – 10 | 3 |
| 10 – 20 | 8 |
| 20 – 30 | 14 |
| 30 – 40 | 9 |
| 40 – 50 | 4 |
| 50 – 60 | 2 |
उत्तर
Let assumed mean A = 25
| C.I. marks |
xi | fi | di = xi – A | fidi |
| 0 – 10 | 5 | 3 | – 20 | – 60 |
| 10 – 20 | 15 | 8 | – 10 | – 80 |
| 20 – 30 | 25 = A | 14 | 0 | 0 |
| 30 – 40 | 35 | 9 | 10 | 90 |
| 40 – 50 | 45 | 4 | 20 | 80 |
| 50 – 60 | 55 | 2 | 30 | 60 |
| n = 40 | `sumf_i d_i` = 90 |
Mean = `A + (sumf_i d_i)/n`
= `25 + 90/40`
= 25 + 2.25
= 27.25 marks
APPEARS IN
संबंधित प्रश्न
Find the missing frequency (p) for the following distribution whose mean is 7.68.
| x | 3 | 5 | 7 | 9 | 11 | 13 |
| f | 6 | 8 | 15 | P | 8 | 4 |
The arithmetic mean of the following data is 14. Find the value of k
| x1 | 5 | 10 | 15 | 20 | 25 |
| f1 | 7 | k | 8 | 4 | 5 |
The arithmetic mean of the following data is 25, find the value of k.
| x1 | 5 | 15 | 25 | 35 | 45 |
| f1 | 3 | k | 3 | 6 | 2 |
The following distribution gives the number of accidents met by 160 workers in a factory during a month.
| No. of accidents(x) | 0 | 1 | 2 | 3 | 4 |
| No. of workers (f) | 70 | 52 | 34 | 3 | 1 |
Find the average number of accidents per worker.
If the mean of the following frequency distribution is 18, find the missing frequency.
| Class interval | 11 – 13 | 13 – 15 | 15 – 17 | 17 – 19 | 19 – 21 | 21 – 23 | 23 – 25 |
| Frequency | 3 | 6 | 9 | 13 | f | 5 | 4 |
If the mean of 6, 7, x, 8, y, 14 is 9, then ______.
The mean of first n odd natural numbers is \[\frac{n^2}{81}\],then n =
There are 45 students in a class, in which 15 are girls. The average weight of 15 girls is 45 kg and 30 boys is 52 kg. Find the mean weight in kg of the entire class.
Mean of 100 items is 49. It was discovered that three items which should have been 60, 70, 80 were wrongly read as 40, 20, 50 respectively. The correct mean is ______.
Using step-deviation method, find mean for the following frequency distribution:
| Class | 0 – 15 | 15 – 30 | 30 – 45 | 45 – 60 | 60 – 75 | 75 – 90 |
| Frequency | 3 | 4 | 7 | 6 | 8 | 2 |
