Question

10 cards are numbered from 1 to 10 and placed in a box. One card is selected at random and is not replaced. Another card is then randomly selected. What is the probability of selecting two prime numbers?

Answer 1

the probability of selecting the first card which is a prime number is $\frac{5}{10}$
the probability of selecting the first card which is a prime number is $\frac{4}{9}$
the probability of selecting two prime numbers is $\frac{5}{10}$×$\frac{4}{9}$=$\frac{2}{9}$

Answer 2

You multiply 5/10 × 4/9 = 2/9

So the answer is 2/9