Louis chooses a whole number from $$1$$ to $$30$$ at random. What is the probability that the number he chooses is a prime number? 
Overseas Competition->Knowledge Point->Counting Modules->Statistics and Probability->Questions Involving Probability->Basic Concepts of Probability
Prime numbers from $$1$$ to $$30$$:  $$2$$, $$3$$, $$5$$, $$7$$, $$11$$, $$13$$, $$17$$, $$19$$, $$23$$, $$29$$  Thus, there are $$10$$ prime numbers from $$1$$ to $$30$$.  Therefore, the probability that the number she chooses is a prime number is $$\frac{10}{30}=\frac{1}{3}$$. 