Find the mean of the prime numbers between 1 and 30.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 12.9
The mean is the sum of the numbers divided by how many there are. A prime number has two different factors, 1 and itself; 1 has only one factor, so it is not prime.
Primes between 1 and 30: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 — 10 numbers
Sum \(=2+3+5+7+11+13+17+19+23+29=129\)
Mean \(\displaystyle =\frac{129}{10}=12.9\)