Advertisements
Advertisements
प्रश्न
Find the number of pairs of observations from the following data,
r = 0.15, `sigma_"y"` = 4, `sum("x"_"i" - bar"x")("y"_"i" - bar"y")` = 12, `sum("x"_"i" - bar"x")^2` = 40.
Advertisements
उत्तर
Given, r = 0.15, `sigma_"y"` = 4, `sum("x"_"i" - bar"x")("y"_"i" - bar"y") `= 12, `sum("x"_"i" - bar"x")^2` = 40
Since, `sigma_"x" = sqrt(1/"n" sum("x"_"i" - bar"x")^2) = sqrt(40/"n"`
Cov (x, y) = `1/"n" sum("x"_"i" - bar"x")("y"_"i" - bar"y")`
= `1/"n" xx 12`
∴ Cov (x, y) = `12/"n"`
Since, r = `("Cov (x, y)")/(sigma_"x" sigma_"y")`
∴ 0.15 = `(12/"n")/(sqrt(40/"n") xx 4)`
∴ 0.15 = `3/("n" xx sqrt(40/"n")`
∴ 0.15 = `1/(sqrt("n") xx sqrt(40)`
Squaring on both the sides, we get
0.0025 = `1/("n" xx 40)`
∴ n = `1/(0.0025 xx 40)`
= `10000/(25 xx 40)`
= `10000/1000`
∴ n = 10
APPEARS IN
संबंधित प्रश्न
Find correlation coefficient between x and y series for the following data.
n = 15, `bar"x"` = 25, `bar"y"` = 18, σx = 3.01, σy = 3.03, `sum("x"_"i" - bar"x") ("y"_"i" - bar"y")` = 122
The correlation coefficient between two variables x and y are 0.48. The covariance is 36 and the variance of x is 16. Find the standard deviation of y.
In the following data one of the value y of is missing. Arithmetic means of x and y series are 6 and 8 respectively. `(sqrt(2) = 1.4142)`
| x | 6 | 2 | 10 | 4 | 8 |
| y | 9 | 11 | ? | 8 | 7 |
Calculate the correlation coefficient
Find correlation coefficient from the following data. `["Given:" sqrt(3) = 1.732]`
| x | 3 | 6 | 2 | 9 | 5 |
| y | 4 | 5 | 8 | 6 | 7 |
Correlation coefficient between x and y is 0.3 and their covariance is 12. The variance of x is 9, Find the standard deviation of y.
Two series of x and y with 50 items each have standard deviations of 4.8 and 3.5 respectively. If the sum of products of deviations of x and y series from respective arithmetic means is 420, then find the correlation coefficient between x and y.
Given that r = 0.4, `sigma_"y"` = 3, `sum("x"_"i" - bar"x")("y"_"i" - bar"y")` = 108, `sum("x"_"i" - bar"x")^2` = 900. Find the number of pairs of observations.
Given the following information, `sum"x"_"i"^2` = 90, `sum"x"_"i""y"_"i"` = 60, r = 0.8, `sigma_"y"` = 2.5, where xi and yi are the deviations from their respective means, find the number of items.
If the correlation coefficient between x and y is 0.8, what is the correlation coefficient between 2x and y
If the correlation coefficient between x and y is 0.8, what is the correlation coefficient between `"x"/2` and y
If the correlation coefficient between x and y is 0.8, what is the correlation coefficient between x and 3y
If the correlation coefficient between x and y is 0.8, what is the correlation coefficient between x – 5 and y – 3
If the correlation coefficient between x and y is 0.8, what is the correlation coefficient between x + 7 and y + 9
If the correlation coefficient between x and y is 0.8, what is the correlation coefficient between `("x" - 5)/7` and `("y" - 3)/8`?
