Question

Find the mean of the first five prime numbers.

Answer 1

Hint: We will write the first five prime numbers and then add them to find their sum. We will then substitute the values in the formula of mean , ${\text{Mean}} = \dfrac{{{\text{Sum of observations}}}}{{{\text{Number of observations}}}}$ to get the required answer.

Complete step-by-step answer:
We have to find the mean of the first five prime numbers.
Prime numbers are the numbers that have only two factors, the number 1 and the number itself.
The first five prime numbers are 2, 3, 5, 7 and 11.
Mean is calculated by adding all the observations by the total number of observations.
The formula of mean is $\dfrac{{{\text{Sum of observations}}}}{{{\text{Number of observations}}}}$
Therefore, we will calculate the sum of the first five prime numbers.
$
   \Rightarrow 2 + 3 + 5 + 7 + 11 \\
   \Rightarrow 28 \\
$
Now, we will divide this by 5 as there are a total 5 numbers.
$\dfrac{{28}}{5} = 5.6$
Hence, the mean of first five prime numbers is 5.6

Note: Mean is also known as average. Many students consider all odd numbers as prime numbers but there are odd numbers which are not prime. For example, 9 is an odd number and has 3 factors, 1, 3 and 9, and hence not a prime number. The number 1 is neither a prime nor a composite number.