Answer: The required percentage is 40%.
Step-by-step explanation: We are given to find the percentage of the first 20 natural numbers that are prime.
We know that
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
[tex]P(A)=\dfrac{n(A)}{n(S)}=\dfrac{8}{20}=\dfrac{2}{5}\times100\%=40\%.[/tex]
Thus, the required percentage is 40%.
