M = {14, 11, 7, 9, 10, 13} Which of the following statements is tru
[#permalink]
16 Dec 2024, 14:29
The given set M is $\{-14,-11,-7,9,10,13\}$ whose range (= Highest value - Smallest value) is 13 -(-14)=13+14=27$
Median of the set $M$, having 6 values is the average of the $3^{\text {rd \&$ the $4^{\text {th $ term $=\frac{-7+9}{2}=\frac{2}{2}=1 \&$ the arithmetic mean (average) of the set $M$ is
$=\frac{-14+(-11)+(-7)+9+10+13}{6}=\frac{0}{6}=0$
Finally we can find the standard deviation of set M about the mean $(=\overline{\mathrm{X)$ i.e. about 0 so we get
\begin{tabular}{|l|l|l|} \hline x_i$ & x_i- Mean $=x_i-0 & \left(x_i-\text { Mean }\right)^2 \\ \hline-14 & -14 & 196 \\ \hline-11 & -11 & 121 \\ \hline-7 & -7 & 49 \\ \hline 9 & 9 & 81 \\ \hline 10 & 10 & 100 \\ \hline 13 & 13 & 169 \\ \hline & {$\sum\left(x_i-\bar{X}\right)^2=716$} \\ \hline \end{tabular}
So, the standard deviation is $\sqrt{\frac{\sum\left(x_i-\bar{X}\right)^2}{n}}=\sqrt{\frac{716}{6}}=\sqrt{119.3} \approx 10.92$
Now, checking from the statements
I. Median is greater than mean - which is true as Median $=1>$ Mean $=0$
II. Standard deviation is greater than range - which is false as standard deviation $=10.92< Range =27$
III. Mean is greater than median - which is false as Mean $=0< Median =1$
Hence only statement I is true, so the answer is (A).