d The average of first ten prime numbers odd

# Arithmetic MCQ 6 (Average of given numbers)

MCQ 6: The average of first ten prime numbers which are odd is____________?

a) 12.9                    b) 13.8                      c) 15.8                   d) 17

Solution:

Prime numbers  ( or primes) are the numbers which are divisible by themselves or by 1

They start from ;

2 , 3, 5, 7 , 11, 13, 17, 21, 23, 27, 31, 37 …………….and so on !

But we have been given the first ten odd PNs which are;

3, 5, 7 , 11, 13, 17, 21, 23, 27, 31

To find their average we use ;

$Average = \frac{Sum Of Terms}{Total Number Of Terms}$

Here sum is;

3+5+7+11+13+17+21+23+27+31 =158

And total number of terms i-e total number of odd prime numbers is 10

so,

$Average = \frac{158}{10}=15.8$

i-e  option c is correct

### The average of the first ten primes which are odd is

are divisible by themselves only.

2 is the only even prime number.

The question is about  first 10 PNs excluding 2.

Primes are all odd except 2 but all primes are not odd.

Odd numbers are divisible not by 2.

1 is a prime number,
all primes are infinite,
define prime number divisible by themselves.
2 is a prime number which is even,
primes are never-ending,

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