1
NDA 2018 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
In which one of the following cases would you expect to get negative correlation?
A
The ages of husbands and wifes
B
Shoe size and intelligence
C
Insurance companies profits and the number of claims they have to pay
D
Amount of rainfall and yield of crop
2
NDA 2018 Paper 1
MCQ (Single Correct Answer)
+2.5
-0.83
If the correlation coefficient between x and y is 0.6, covariance is 27 and variance of y is 25, then what is the variance of x?
A
$${9 \over 5}$$
B
$${81 \over 25}$$
C
9
D
81
3
NDA 2018 Paper 1
MCQ (Single Correct Answer)
+2.5
-0.83
Let $$\overline x $$ be the mean of x1, x2, x3, ....., xn. If xi = a + cyi for some constants a and c, then what will be the mean of y1, y2, y3, ....., yn ?
A
a + c$$\overline x $$
B
a $$-$$ $${1 \over c}\overline x $$
C
$${1 \over c}\overline x $$ $$-$$ a
D
$${{\overline x - a} \over c}$$
4
NDA 2018 Paper 1
MCQ (Single Correct Answer)
+2.5
-0.83
Consider the following statements

I. If the correlation coefficient rxy = 0, then the two lines of regression are parallel to each other.

II. If the correlation coefficient rxy = 1, then the two lines of regression are perpendicular to each other.

Which of the above statements is/are correct?
A
Only I
B
Only II
C
Both I and II
D
Neither I nor II
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