Answer:
The primes are 2, 3, 5, 7, 11, 13, 17, 19. There are 8 of them, so they make up 40% of the numbers 1–20.
Step-by-step explanation:
We are given to find the percentage of the first 20 natural numbers that are prime.
We know that the first 20 natural numbers are 1, 2, 3, 4, . . . , 19, 20.
And, the prime numbers among them are 2, 3, 5, 7, 11, 13, 17 and 19.
So, if S be the sample space for the experiment and A be the event of selecting a prime number.
Then, we have n(S) = 20 and n(A) = 8.
Therefore, the probability of event A is given by
P(A) = n(A) / n(S) = 8/20 = 2/5 x 100% = 40%
Thus, the required percentage is 40%.
