Ans: A
The mean $a$
The mean $a$
$\begin{array}{cl}
= & \dfrac{x+x+ \cdots + (x+2) + (x+3)}{10} \\
= & \dfrac{10x+7}{10} \\
= & x + \dfrac{7}{10}
\end{array}$
The median $b=x$.
The mode $c =x$.
The range $d$
$\begin{array}{cl}
= & (x+3) – x \\
= & 3
\end{array}$
I must be true. According to the above calculation, $a>b$.
II must be false. According to the above calculation, $b=c$.
III may be false. $x$ can be greater than, equal to or smaller than $3$.
