What is the standard deviation of the following series

class

0-10

10-20

20-30

30-40

Freq

1

3

4

2

  • A

    $81$

  • B

    $7.6$

  • C

    $9$

  • D

    $2.26$

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What is the standard deviation of the following series

class $0-10$ $10-20$ $20-30$ $30-40$
Freq $1$ $3$ $4$ $2$

 

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