The following table relates the number of objects f corresponding to a certain size x....

JAMB 1979

The following table relates the number of objects f corresponding to a certain size x. What is the average size of an object?
\(\begin{array}{c|c} f & 1 & 2 & 3 & 4 & 5 \\ \hline x & 1 & 2 & 4 & 8 & 16\end{array}\)

A. \(\frac{31}{15}\)
B. \(\frac{31}{5}\)
C. \(\frac{129}{5}\)
D. \(\frac{43}{5}\)
E. \(\frac{16}{5}\)

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Correct Answer: Option D

Explanation

F = 1, 2, 3, 4, 5

x = 1, 2, 4, 8, 16

fx = 1, 4, 12, 32, 80, 3f = 15

(average size) = \(\frac{\sum fx}{\sum f}\)

= \(\frac{129}{15}\)

= \(\frac{43}{5}\)

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