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A sample of 35 observations has the mean...

A sample of 35 observations has the means 80 and SD. As 4. A second sample of 65 observations from the same population has mean 70 and S.D.3. The S.D. of the combined sample is -

A

`5*85`

B

`37*2`

C

`5*58`

D

none of these

Text Solution

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The correct Answer is:
A
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Knowledge Check

  • A sample of 35 observations has the mean 80 and standard deviation as 4. A second sample of 65 observations from the same population has mean 70 and standard deviation 3. Then, the standard deviation of the combined sample is

    A
    `5.85`
    B
    `5.58`
    C
    `34.2`
    D
    None of these

  • A sample of 90 values has standard deviation 3 and their mean is 55. A second sample of 110 values has mean 60 and its standard deviation is 2. The combined variance is equal to

    A
    `12.44`
    B
    `13.24`
    C
    `16.42`
    D
    `13.65`

  • A sample of 90 values has mean 55 and standard deviation 3. A second sample of 110 values has mean 60 and standard deviations 2. The combined variance is equal to (upto two decimal)

    A
    `12.43`
    B
    ` 11.24`
    C
    ` 10.43`
    D
    `13.25`

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