What is the average of all the prime numbers between 10 and 25?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 16.6
A prime number has no factor other than 1 and itself. First list the primes in the range, then divide their sum by how many there are.
Primes between 10 and 25: 11, 13, 17, 19, 23 (15 and 21 are divisible by 3)
Sum \(=11+13+17+19+23=83\)
\(\displaystyle \text{Average}=\frac{83}{5}=16.6\)
The average of the primes is 16.6.