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begin array c c x amp 1 amp 2 amp 3 amp 4 amp 5... - JAMB Mathematics 1994 Question

\(\begin{array}{c|c} x & 1 & 2 & 3 & 4 & 5 \ \hline f & 2 & 1 & 2 & 1 & 2\end{array}\)
Find the variance of the frequency distribution above
A
\(\frac{3}{2}\)
B
\(\frac{9}{4}\)
C
\(\frac{5}{2}\)
D
3
correct option: b
\(\begin{array}{c|c} x & f & fx & \bar{x} - x & (\bar{x} - x)^2 & f(\bar{x} - x)^2 \ \hline 1 & 2 & 2 & -2 & 4 & 8\ 2 & 1 & 2 & -1 & 1 & 1\ 3 & 2 & 6 & 0 & 0 & 0\ 4 & 1 & 4 & 1 & 1 & 1\ 2 & 2 & 10 & 2 & 4 & 8\ \hline & 8 & 24 & & & 18 \end{array}\)

x = \(\frac{\sum fx}{\sum f}\)

= \(\frac{24}{8}\)

= 3

Variance (62) = \(\frac{\sum f(\bar{x} - x)^2}{\sum f}\)

= \(\frac{18}{8}\)

= \(\frac{9}{4}\)
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