Question

The Standard deviation of the following frequency distribution

CI:	0 - 6	6 - 12	12 - 18
fi:	2	4	6

is ______.

Options

• 25

• 20

• `2sqrt(5)`

• 12

Answer 1

The Standard deviation of the following frequency distribution

CI:	0 – 6	6 – 12	12 – 18
fi:	2	4	6

is `2sqrt(5)`.

Explanation:

Here,

N = `sum"f"_"i" = 12, sum"f"_"i"x_"i" = 132, sum"f"_"i"x_"i"^2` = 1692

∴ V(X) = `1692/12 - (132/12)^2`

= 141 – 121

= 20

S.D = `sqrt(20) = 2sqrt(5)`