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23. Why there are two regression equations?
24. What are the uses of regression analysis?
25. Distinguish between correlation and regression.
26. What do you mean by regression line of Y on X and
regression line of X on Y?
27. From the following data, find the regression equation
X = 21, Y = 20, X2 = 91, XY = 74, n = 7
28. From the following data find the regression equation of Y on
X. If X = 15, find Y?
X8
11
7
10 12 5
4
6
Y 11 30
25 44 38 25 20 27
29. Find the two regression equations from the following data.
X
25 22 28 26 35 20 22 40 20 18
Y
18 15 20 17 22 14 16 21 15 14
30. Find S.D (Y), given that variance of X = 36, bxy = 0.8,
r = 0.5
31. In a correlation study, the following values are obtained
X
Y
Mean
68 60
S.D.
2.5 3.5
Coefficient of correlation, r = 0.6 Find the two regression
equations.
239 32. In a correlation studies, the following values are obtained:
X
Y
Mean
12 15
S.D.
2
3
r = 0.5 Find the two regression equations.
33. The correlation coefficient of bivariate X and Y is r=0.6,
variance of X and Y are respectively, 2.25 and 4.00, X =10,
Y =20. From the above data, find the two regression lines
34. For the following lines of regression find the mean values of
X and Y and the two regression coefficients
8X10Y+66=0
40X18Y=214
35. Given X=90, Y=70,bxy = 1.36, byx = 0.61
Find (i) the most probable values of X, when Y = 50 and
(ii) the coefficient of correlation between X and Y
36. You are supplied with the following data:
4X5Y+33 = 0 and 20X9Y107 = 0
variance of Y = 4. Calculate
(I)
Mean values of x and y
(II)
S.D. of X
(III) Correlation coefficients between X and Y.
Answers:
I. 1. b 2. c
3.d
4. b 5. b 6. a
7. a
8. a
9. c
10. b
II.
11. dependence 12. dependence 13. more than, less than
14. lesser 15. positive 16. same.
III.
27. Y = 0.498X +1.366 28. Y =1.98X + 12.9;Y=42.6 30. 3.75
31. Y=2.88 + 0.84X, X = 42.2 + 0.43Y
32. Y = 6 + 0.75X ; X = 7 + 0.33Y
33. Y= 0.8X + 12, X = 0.45Y +1
34. X =13, Y = 17 byx = 9/20, bxy = 4/5
35. (i) 62.8, (ii) 0.91
36. X =13, Y =17, S.D(X)=9, r = 0.6
240...
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 Winter '08
 Moshiri
 Business

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