Question

Find the mean of the first five multiples of $7$?
$\left(a\right)\text{ 18}$
$\left(b\right)\text{ 20}$
$\left(c\right)\text{ 15}$
$\left(d\right)\text{ 24}$

Answer 1

Hint: First of all we have to add the first five multiples of $7$ and then we have to find the mean. For mean, we will divide the added number by the total number of terms. In our case the total number of terms will be $5$, so we will divide it by $5$. And in this way, we can solve this problem.

Formula used:
Formula for the mean will be mean,
$m={\displaystyle \frac{Sum\text{ of terms}}{Number\text{ of terms}}}$
Here,
$m$, will be the mean.

Complete step-by-step answer:
 The first five multiples $7$ will be –
$7,14,21,28\text{ and }35$
Now we will find the mean so for this we have to use the mean formula, which is
$m={\displaystyle \frac{Sum\text{ of terms}}{Number\text{ of terms}}}$
Here the number of terms is $5$
And the sum of terms will be calculated as $105$
Therefore,
$\Rightarrow m={\displaystyle \frac{7+14+21+28+35}{5}}$
On solving the above equation, we get
$\Rightarrow m={\displaystyle \frac{105}{5}}$
On dividing, we get
$\Rightarrow m=21$
Therefore, $21$ will be the mean of the first five multiples $7$.

Additional information: The cycle for finding the mean of a gathering of numbers is as per the following: Add together all the numbers for which we require to locate the normal. Separation this entirety by the number equivalent to the number of numbers we have added together.

Note: For mean questions, they will raise for the common of a group with variables, or they will raise to search out the worth to that the total of a group of numbers should be raised or lowered to search out a specific average. Just detain mind, that despite how odd the question seems to be, the method for locating the mean is unchanging.