Question

Out of $100$ numbers $20$ were $5s$, $30$ were $6s$ and the remaining were $7s$. The arithmetic mean of the numbers is

• A. $6.3$
• B. $5.4$
• C. $6.1$
• D. $6.5$

Answer 1

The correct option is A $6.3$

$\text{Since, arithmetic mean =}\overline{x}=\frac{\text{Sum of Observations}}{\text{numbers of observations}}$
$\overline{x}=\frac{20\times 5+30\times 6+50\times 7}{100}$
$\Rightarrow \overline{x}=\frac{100+180+350}{100}$
$\Rightarrow \overline{x}=\frac{630}{100}$
$\Rightarrow \overline{x}=6.3$