Question

Find the mean of first n natural numbers. Also find the mean of all prime numbers less than 20.

Answer 1

Answer:

hope you got your answer

Answer 2

Answer:

The mean of first n natural numbers is $\frac{n + 1}{2}$

and mean of all prime numbers less than 20 is 9.625.

Step-by-step explanation:

We know,

mean $= \frac{sum \: of \: numbers}{total \: numbers}$

We know sum of first natural numbers $= \frac{n(n + 1)}{2}$

So, mean of first natural numbers

$= \frac{ \frac{n(n + 1)}{2} }{n} \\ = \frac{n(n + 1)}{2 \times n} \\ = \frac{n + 1}{2}$

Again,we want to find mean of all prime numbers less than 20.

We know, prime numbers less than 20 are 2,3,5,7,11,13,17,19.

So according to rule mean of oall prime numbers less than 20

$= \frac{2 + 3 + 5 + 7 + 11 + 13 + 17 + 19}{8} \\ = \frac{77}{8} \\ = 9.625$

So, required mean is 9.625.

Know more about mean:

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