NDA 2018 Paper 2 | Statistics Question 44 | Mathematics

In any discrete series (when all values are not same), if x represents mean deviation about mean and y represents standard deviation, then which one of the following is correct?

y $$\ge$$ x

y $$\le$$ x

x = y

x < y

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?

The ages of husbands and wifes

Shoe size and intelligence

Insurance companies profits and the number of claims they have to pay

Amount of rainfall and yield of crop

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?

$${9 \over 5}$$

$${81 \over 25}$$

NDA 2018 Paper 1

MCQ (Single Correct Answer)

+2.5

-0.83

Let $$\overline x $$ be the mean of x₁, x₂, x₃, ....., x_n. If x_i = a + cy_i for some constants a and c, then what will be the mean of y₁, y₂, y₃, ....., y_n ?

a + c$$\overline x $$

a $$-$$ $${1 \over c}\overline x $$

$${1 \over c}\overline x $$ $$-$$ a

$${{\overline x - a} \over c}$$

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