NDA 2016 Paper 2 | Statistics Question 6 | Mathematics

For 10 observations on price (x) and supply (y), the following data was obtained.

$$\Sigma$$x = 130, $$\Sigma$$y = 220, $$\Sigma$$x² = 2288, $$\Sigma$$y² = 5506 and $$\Sigma$$xy = 3467.

What is the line of regression of y on x?

y = 0.91 x + 8.74

y = 1.02 x + 8.74

y = 1.02 x $$-$$ 7.02

y = 0.91 x $$-$$ 7.02

NDA 2016 Paper 2

MCQ (Single Correct Answer)

+2.5

-0.83

In a study of two groups, the following results were obtained.

Image

Which of the following statements is correct?

Group A is less variable than Group B because Group A's standard deviation is smaller

Group A is less variable than Group B because Group A's sample size is smaller

Group A is less variable than Group B because Group A's sample mean is smaller

Group A is less variable than group B because Group A's coefficient of variation is smaller

NDA 2016 Paper 2

MCQ (Single Correct Answer)

+2.5

-0.83

Consider the following statements in respect of class intervals of grouped frequency distribution.

I. Class-intervals need not be mutually exclusive.

II. Class-intervals should be exhaustive

III. Class-intervals need not be of equal width

Which of the above statements are correct?

I and II

II and III

I and III

I, II and III

NDA 2016 Paper 2

MCQ (Single Correct Answer)

+2.5

-0.83

Two variates, x and y are uncorrelated and have standard deviations $$\sigma$$_x and $$\sigma$$_y respectively. What is the correlation coefficient between x + y and x $$-$$ y ?

$${{{\sigma _x}{\sigma _y}} \over {\sigma _x^2 + \sigma _y^2}}$$

$${{{\sigma _x} + {\sigma _y}} \over {2{\sigma _x}{\sigma _y}}}$$

$${{\sigma _x^2 - \sigma _y^2} \over {\sigma _x^2 + \sigma _y^2}}$$

$${{{\sigma _y} - {\sigma _x}} \over {{\sigma _x}{\sigma _y}}}$$

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