Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 1

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IMPORTANT

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If a variate $X$ is expressed as a linear function of two variates $U$ and $V$ in the form $X = a U + b V,$ then Mean $\bar{X}$ of $X$ is

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Important Questions on Statistics

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IMPORTANT

Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 2

In a group of students, the mean weight of boys is

65 kg

, and mean weight of girls is

55 kg

. If the mean weight of all students of group is

61 kg

, then the ratio of the number of boys and girls in the group is

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Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 3

If the mean of

n

observations

1^{2}, 2^{2}, 3^{2}, . . . . . . n^{2}

is

\frac{46 n}{11}

, then

n

is equal to

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Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 4

If

{\bar{x}}_{1}

and

{\bar{x}}_{2}

are means of two distribution, such that

{\bar{x}}_{1} < {\bar{x}}_{2}

and

\bar{x}

is the mean of the joint distribution, then

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Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 5

If the variance of

10

natural numbers

1, 1, 1, \dots, 1, k

is less than

10,

then the maximum possible integral value of

k

is ___________.

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IMPORTANT

Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 6

The first of the two samples in a group has

100

items with mean

15

and standard deviation

3 .

If the whole group has

250

items with mean

15.6

and standard deviation

\sqrt{13.44},

then the standard deviation of the second sample is:

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Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 7

For the set

A = \{x_{1}, x_{2}, x_{3}, x_{4}, x_{5}\}

the variance is

4

and the mean is

2 .

For the set

B = \{y_{1}, y_{2}, y_{3}, y_{4}, y_{5}\}

the variance is

5

and the mean is

4 .

Then the variance of

A \cup B

is

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Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 8

In any discrete series (when all the value are not same) the relationship between

M . D .

about mean and

S . D .

is-

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Mathematics Crash Course JEE Main>Chapter 27 - Statistics>Level 2>Q 9

The standard deviation in a variable

x

is

σ

. The standard deviation of the variable

\frac{a x + b}{c}

; where

a, b

and

c

are constants, is