(begin{array}{c|c}
Class Interval & 3 – 5 & 6 – 8 & 9 – 11 \ hline Frequency & 2 & 2 & 2 end{array}). Find the standard deviation of the above distribution.
Class Interval & 3 – 5 & 6 – 8 & 9 – 11 \ hline Frequency & 2 & 2 & 2 end{array}). Find the standard deviation of the above distribution.
-
A.
√5 -
B.
√6 -
C.
√7 -
D.
√2
Correct Answer: Option B
Explanation
(begin{array}{c|c}Class Interval & 3 – 3 & 6 – 8 & 9 – 11 \ x & 4 & 7 & 10 \ f & 2 & 2 & 2 \ f – x & 8 & 14 & 20 \ |x – bar{x}|^2 & 9 & 0 & 9 \ |x – bar{x}|^2 & 18 0 & 18 end{array})
(bar{x}) = (frac {sum fx}{sum f})
= (frac {8 + 14 + 20}{2 + 2 + 2})
= (frac{42}{6})
(bar{x}) = 7
S.D = (sqrtfrac{sum f(x – bar{x})^2}{sum f})
= (sqrtfrac{18 + 0 + 18}{6})
= (sqrtfrac{36}{6})
= (sqrt {6})