EASY

Earn 100

The time taken for telephone calls to a call centre to be answered is normally distributed with mean $20$ seconds and standard deviation $5$ seconds. Find the probability that for $16$ randomly selected calls made to the centre, the mean time taken to answer the calls is less than $18$ seconds. (Correct your answer up to four decimal places).

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Important Questions on Sampling

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

The mean and variance of a binomial distribution are

8

and

4

respectively, then

P (X = 1)

is equal to

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

The marks obtained by students $A$ and $B$ in $3$ examinations are given below

Marks of $A$	$30$	$20$	$40$
Marks of $B$	$70$	$0$	$5$

The ratio of the coefficient of variation of marks of $A$ and the coefficient of variation of marks of $B$ is

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

The variance of

20

observations is

5 .

If each observation is multiplied by

2,

then the variance of the resulting observation is

EASY

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

A random variable

X ∽ B (n, p) .

If values of mean and variance of

X

are

18

and

12

respectively then total number of possible values of

X

are

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

Coefficient of variation of two distributions are

50

and

60

and their arithmetic means are

30

and

25

, respectively. Difference of their standard deviation is

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

Coefficient of variation of two distributions are

60

and

70

, and their standard deviation are

21

and

16

, respectively. What are their arithmetic means?

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

Coefficient of variation of two distributions are

60

and

70

and their standard deviations are

21

and

16

respectively. Then their AM's are

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

X

is a Poisson random variable such that

E (X^{2}) = 30

, then the variance of

X

is -

EASY

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

Find the least positive value of

k

, if the range of

15, 14, k, 25, 30, 35

23

EASY

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

The range of the observations

20, 28, 40, 12, 30, 15, 50

is _____

EASY

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

65

is the range of the ungrouped data

50, 70, 60, B, 20, 40

then the absolute difference of the possible values of

B

EASY

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

The mean and variance of a binomial variable

X

are

2

and

1

respectively. The probability that

X

takes values greater than

1

, is

EASY

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

If the mean of a data

\bar{x}

10

and if all the observations are multiplied by

2

, then the mean of new data is

EASY

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

3 %

of the electric bulbs manufactured by a company are defective, the probability that in a sample of

100

bulbs exactly

5

bulbs are defective is

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

For a normal curve, the greatest ordinate is

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

The average runs scored by a batsman in

15

cricket matches is

60

and standard deviation of the runs is

15

. Find the coefficient of variation of the runs scored by him.

HARD

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

In a Poisson distribution,

P (X = 2) = P (X = 3)

. Given that

e^{- 3} = 0.050

. Then

P (X = 5)

is -

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

The means of two groups of observations

A

and

B

are

\vec{x}, \vec{y}

respectively and their standard deviations are respectively

2

and

3 .

In order that the group

A

is to be more consistent than the group

B,

\frac{\vec{y}}{\vec{x}} <

MEDIUM

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

In a binomial distribution the mean is

15

and variance is

10 .

Then parameter

n

HARD

Mathematics (9709)>P-6: Statistics and Probability 2>Sampling>The Distribution of Sample Means

A box contains

15

green and

10

yellow balls. If

10

balls are randomly drawn, one-by-one, with replacement, then the variance of the number of green balls drawn is:

Important Questions on Sampling

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