Class Interval3−56−89−11Frequency222 Class Interval 3 − 5 6 − 8 9 − 11 Frequency 2 2 2 . Find the standard deviation of the above distribution.

Assessment: JAMB UTME - Mathematics - 2011 Subject: General Mathematics

Question 1 Report

$\begin{array}{cc} Class Interval & 3 - 5 & 6 - 8 & 9 - 11 \\ Frequency & 2 & 2 & 2 \end{array}$ .

Find the standard deviation of the above distribution.

√5

√6

√7

√2

Answer Details

$\begin{array}{cc} Class Interval & 3 - 3 & 6 - 8 & 9 - 11 \\ x & 4 & 7 & 10 \\ f & 2 & 2 & 2 \\ f - x & 8 & 14 & 20 \\ | x - \bar{x} |^{2} & 9 & 0 & 9 \\ | x - \bar{x} |^{2} & 180 & 18 \end{array}$
$\bar{x}$ = $\frac{\sum f x}{\sum f}$
= $\frac{8 + 14 + 20}{2 + 2 + 2}$
= $\frac{42}{6}$
$\bar{x}$ = 7
S.D = $\sqrt{\frac{\sum f (x - \bar{x})^{2}}{\sum f}}$
= $\sqrt{\frac{18 + 0 + 18}{6}}$
= $\sqrt{\frac{36}{6}}$
= $\sqrt{6}$

Read lesson note on Measures Of Dispersion (JAMB)

Measures Of Dispersion

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Class Interval3−56−89−11Frequency222 Class Interval 3 − 5 6 − 8 9 − 11 Frequency 2 2 2 . Find the standard deviation of the above distribution.

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