A batsman scores runs in 10 innings as 38,70,48,34,42,55,63,46,54 and 44 , then the mean score is

**A. ** 494

**B. ** 0.494

**C. ** 4.94

**D. ** 49.4

**Answer : ****Option D**

**Explaination / Solution: **

Mean (*x*) =

= 494/10

= 49.4

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The mean of 5 observations is 4.4. If three observations are 1,2 and 6 and the difference of the other two is 5, then the other two observations are:

**A. ** 5 and 9

**B. ** 9 and 4

**C. ** 4 and 8

**D. ** 5 and 7

**Answer : ****Option B**

**Explaination / Solution: **

Let other two numbers be *x *and *y *

Mean (*x*) = 4.4 =

this gives ......(1)

Also, * ........*(2)

Therefore from (1) and (2)

x = 9 and * y = 4*

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Which one of the following average is most affected of extreme observations ?

**A. ** G.M.

**B. ** Mode

**C. ** Median

**D. ** A. M.

**Answer : ****Option D**

**Explaination / Solution: **

As A/M is calculated as the sum of all the observations divided by number of observations, so it is affected by if there is any change in the outliers

As A/M is calculated as the sum of all the observations divided by number of observations, so it is affected by if there is any change in the outliers

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S.D. of a data is 6. When each observation is increased by 1, then the S.D. of new data is

**A. ** 7

**B. ** 8

**C. ** 5

**D. ** 6

**Answer : ****Option D**

**Explaination / Solution: **

so it depends only on number of observations not on individual observations.

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If the coefficient of variation between x and y is 0.28, covariance between x and y is 7.6, and the variance of x is 9, then the S.D. of the y series is

**A. ** 10.05

**B. ** 9.8

**C. ** 9.05

**D. ** 10.1

**Answer : ****Option C**

**Explaination / Solution: **

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If the mean of the squares of first n natural numbers be 11, then n is equal to

**A. ** - 13/ 2

**B. ** 13

**C. ** 5

**D. ** 11

**Answer : ****Option C**

**Explaination / Solution: **

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If the two lines of regression are at right angles , then ρ(X,Y) is equal to

**A. ** 1

**B. ** -1

**C. ** 0

**D. ** 1 or - 1

**Answer : ****Option C**

**Explaination / Solution: **

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If mean = ( 3 median – mode ) x , then the value of x is

**A. ** 1/2

**B. ** 2

**C. ** 3/2

**D. ** 1

**Answer : ****Option A**

**Explaination / Solution: **

We know that, 3median = mode + 2 mean

so, mean= (3 median - mode)/2 ........(1)

comparing equation(1) with the given equation

therefore, x=1/2

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Which of the following is not a measure of dispersion ?

**A. ** mean deviation

**B. ** variance

**C. ** range

**D. ** mean

**Answer : ****Option D**

**Explaination / Solution: **

it is the measure of central tendency

it is the measure of central tendency

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If the two lines of regression are 2x + y =7 and x + 2y = 7, then ρ(X,Y) is equal to

**A. ** -1/4

**B. ** - 1/ 2

**C. ** 1/ 4

**D. ** 1/ 2

**Answer : ****Option B**

**Explaination / Solution: **

let us assume that 2x + y =7 and x + 2y = 7 are lines of regression of y on x and x on y respectively

therefore,

but sign of p will be same as and

hence,

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