Question

The mean of three numbers is $10$. The mean of other four numbers is $12$. Find the mean of all the numbers.

• A. $13.5$
• B. $11.15$
• C. $12.15$
• D. $14.5$

Answer 1

The correct option is B $11.15$

Given, Mean of $3$ no's $=10$.

Then, total of $3$ no's is $=10\times 3=30$.

Also, Mean of other $4$ no's is $12$.

Then, Total of $4$ no's is $=12\times 4=48$.

$\therefore$Total of $4+3=7$ numbers is $48+30=78$.

We know, Mean is given by,

$\text{Mean}=\frac{\text{Sum of the elements}}{\text{Total number of elements}}$.

Hence, mean of $7$ numbers is $\frac{78}{7}=11.15$ .

Therefore, option $B$ is correct.