Advertisements
Advertisements
प्रश्न
If the mean of the following distribution is 2.6, then the value of y is:
| Variable (x) | 1 | 2 | 3 | 4 | 5 |
| Frequency | 4 | 5 | y | 1 | 2 |
पर्याय
3
8
13
24
उत्तर
8
Explanation:
Consider the following table:
| Variable (x) | Frequency (f) |
fx |
| 1 | 4 | 4 |
| 2 | 5 | 10 |
| 3 | y | 3y |
| 4 | 1 | 4 |
| 5 | 2 | 10 |
| ∑f = 12 + y | ∑fx = 28 + 3y |
Now,
Mean = `(sum"fx")/(sum"f")`
`2.6/1 = (28 + 3y)/(12+y)`
31.2 + 2.6y = 28 + 3y
3y – 2.6y = 31.2 – 28
0.4y = 3.2
y = `(3.2)/(0.4)`
y = 8
संबंधित प्रश्न
The following table gives the number of children of 150 families in a village. Find the average number of children per family.
| No. of children (x) | 0 | 1 | 2 | 3 | 4 | 5 |
| No. of families (f) | 10 | 21 | 55 | 42 | 15 | 7 |
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.
Using an appropriate method, find the mean of the following frequency distribution:
| Class | 84-90 | 90-96 | 96-102 | 102-108 | 108-114 | 114-120 |
| Frequency | 8 | 10 | 16 | 23 | 12 | 11 |
Which method did you use, and why?
The daily expenditure of 100 families are given below. Calculate `f_1` and `f_2` if the mean daily expenditure is ₹ 188.
|
Expenditure (in Rs) |
140-160 | 160-180 | 180-200 | 200-220 | 220-240 |
|
Number of families |
5 | 25 | `f_1` | `f_2` | 5 |
Find the mean of the following frequency distribution, using the assumed-mean method:
| Class | 100 – 120 | 120 – 140 | 140 – 160 | 160 – 180 | 180 – 200 |
| Frequency | 10 | 20 | 30 | 15 | 5 |
The following table shows the marks scored by 80 students in an examination:
| Marks | 0 – 5 | 5 – 10 | 10 – 15 | 15 – 20 | 20 – 25 | 25 – 30 | 30 – 35 | 35 – 40 |
| No. of students |
3 | 10 | 25 | 49 | 65 | 73 | 78 | 80 |
Consider the following distribution of daily wages of 50 workers of a factory:
| Daily wages (in ₹) |
500-520 | 520-540 | 540-560 | 560-580 | 580-600 |
| Number of workers | 12 | 14 | 8 | 6 | 10 |
Find the mean daily wages of the workers of the factory by using an appropriate method.
The value of `sum_(i=1)^nx_i` 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.
The mean of 6 distinct observations is 6.5 and their variance is 10.25. If 4 out of 6 observations are 2, 4, 5 and 7, then the remaining two observations are ______.
