1.What do we expect from the statement "points are very dense".
a. poor correlation
b. good correlation
c. nothing
Ans: a
2. "Correlation coefficient is independent of change of origin and scale". Is it true?
a.Yes
b.No
Ans: Yes
3. Two independent variables are uncorrelated.This implies
a. Cov(X,Y)=0
b. r(X,Y)=0
c. \sigma_{x}\sigma_{y}=0
Ans: a
4.If r is the correlation coefficient then S.E(r)=?
a. \frac{1-n^2}{\sqrt r}
b. \frac{1-r^2}{\sqrt n}
c. \frac{1-r^2}{\sqrt r}
Ans: b
5.Find r(X,Y)
a.0.26
b.0.36
c.0.46
Ans: a
6. If V =X-Y and U =X+Y, Then find the Cov(U,V).
a. \sigma_{x}\sigma_{y}
b. \sigma_{x}+\sigma_{y}
c. \sigma_{x}^2+\sigma_{y}^2
Ans: c
7. The variables X and Y are connected by the relation aX+bY+c=0.The r(X,Y) = - 1. Iff
a. signs of a,b are alike
b. signs of a,b are different
c. None of them
Ans: a
8. To find the proficiency in possession of two characteristics we will use
a. Rank correlation
b. Simple correlation
c. s.d
d. None of them
Ans: a
9. V(aX\pm bY)=?
a. a^2V(X)\pm 2ab Cov(X,Y) +b^2 V(Y)
b. b^2V(X)\pm 2ab Cov(X,Y) +a^2 V(Y)
c. a^2V(X)\pm 2a^2b^2 Cov(X,Y) +b^2 V(Y)
Ans: a
10. The coefficient of variation will have positive sign when
a. X is increasing and Y is decreasing
b. Y is increasing and X is decreasing
c. X is increasing and Y is increasing
Ans: c