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