Advertisements
Advertisements
प्रश्न
Answer the following :
Find variance and S.D. for the following set of numbers: 125, 130, 150, 165, 190, 195, 210, 230, 245, 260
Advertisements
उत्तर
| xi | `x_"i" - barx` | `(x_"i" - barx)^2` |
| 125 | – 65 | 4225 |
| 130 | – 60 | 3600 |
| 150 | – 40 | 1600 |
| 165 | – 25 | 625 |
| 190 | 0 | 0 |
| 195 | 5 | 25 |
| 210 | 20 | 400 |
| 230 | 40 | 1600 |
| 245 | 55 | 3025 |
| 260 | 70 | 4900 |
| `sumx_"i"` = 1900 | `sum(x_"i" - barx)^2` = 20000 |
Here, n = 10
`bar(x) = (sumx_"i")/"n" = 1900/10` = 190
Var (X) = `sigma_x^2 = 1/"n" sum(x_"i" - barx)^2 = 20000/10` = 2000
S.D. = `sigma_x = sqrt("Var(X)")`
= `sqrt(2000)`
= 44.72
APPEARS IN
संबंधित प्रश्न
Find variance and S.D. for the following set of numbers:
7, 11, 2, 4, 9, 6, 3, 7, 11, 2, 5, 8, 3, 6, 8, 8, 2, 6
Find variance and S.D. for the following set of numbers:
65, 77, 81, 98, 100, 80, 129
Following data gives age of 100 students in a college. Calculate variance and S.D.
| Age (In years) | 16 | 17 | 18 | 19 | 20 | 21 |
| No. of Students | 20 | 7 | 11 | 17 | 30 | 15 |
Find mean, variance and S.D. of the following data:
| Classes | 10 – 20 | 20 – 30 | 30 – 40 | 40 – 50 | 50 – 60 | 60 – 70 | 70 – 80 | 80 – 90 | 90 – 100 |
| Frequency | 7 | 14 | 6 | 13 | 9 | 15 | 11 | 10 | 15 |
Find the variance and S.D. of the following frequency distribution which gives the distribution of 200 plants according to their height:
| Height (in cm) | 14 – 18 | 19 – 23 | 24 – 28 | 29 – 33 | 34 – 38 | 39 – 43 | 44 – 48 |
| No. of plants | 5 | 18 | 44 | 70 | 36 | 22 | 5 |
Select the correct option from the given alternatives :
The standard deviation of a distribution divided by the mean of the distribution and expressing in percentage is called:
Select the correct option from the given alternatives :
If the S.D. of first n natural numbers is `sqrt(2)`, then the value of n must be ––––––.
Select the correct option from the given alternatives :
The positive square root of the mean of the squares of the deviations of observations from their mean is called:
Answer the following :
Find variance and S.D. for the following set of numbers:
25, 21, 23, 29, 27, 22, 28, 23, 21, 25
Answer the following :
Compute the variance and S.D. for the following data:
| X | 62 | 30 | 64 | 47 | 63 | 46 | 35 | 28 | 60 |
| F | 5 | 8 | 3 | 4 | 5 | 7 | 8 | 3 | 7 |
Answer the following :
Given below is the frequency distribution of marks obtained by 100 students. Compute arithmetic mean and S.D.
| Marks | 40 - 49 | 50 - 59 | 60 - 69 | 70 - 79 | 80 - 89 | 90 - 99 |
| No. of students | 4 | 12 | 25 | 28 | 26 | 5 |
Find the Standard Deviation of the following data: 14, 22, 9, 15, 20, 17, 12, 11.
If a r.v. X has p.d.f., f(x) = `1/(xlog3)`, for 1 < x < 3, then E(X) and Var(X) are respectively ______
The S.D. and C.V. for the following frequency distribution is
| xi | 60 | 61 | 62 | 63 | 64 | 65 | 66 |
| fi | 3 | 10 | 11 | 13 | 7 | 5 | 1 |
Coefficients of variation of two distributions are 30 and 40 and their arithmetic means are 10 and 25 respectively. The difference of their standard deviations is ______
The S.D. of 20 items is 15 and if each item is decreased or increased by 1, then standard deviation will be ______.
If the S.D. of the data 1, 2, 4, 5, 6, 7, 9 is 2.59, then the S.D. of 3, 6, 12, 15, 18, 21, 27 is ______.
The mean and standard deviation of random variable X are 10 and 5 respectively, then `"E"(("X" - 15)/5)^2` = ______.
Consider three observations a, band c such that b = a + c. If the standard deviation of a + 2, b + 2, c + 2 is d, then which of the following is true?
The mean and standard deviation of 20 observations were calculated as 10 and 2.5 respectively. It was found that by mistake one data value was taken as 25 instead of 35. If α and `sqrtβ` are the mean and standard deviation respectively for correct data, then (α, β) is ______.
If the mean of the data 7, 7, 9, 7, 8, 7, λ, 8 is 7, then the variance of this data is ______.
The mean and variance of 10 observations were calculated as 15 and 15 respectively by a student who took by mistake 25 instead of 15 for one observation. Then, the correct standard deviation is ______.
The mean of a set of observation is `overlinex`. If each observation is divided by α, α ≠ 0 and then is increased by 10, then the mean of the new set is ______.
Let x1, x2 ,..., xn be n observations such that `sumx_1^2` = 400 and `sumx_i` = 80. Then, a possible value of n among the following is:
The variance of first n natural numbers is ______.
