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

You multiply 5/10 × 4/9 = 2/9

So the answer is 2/9

Answer 2

the probability of selecting the first card which is a prime number is
`(5)/(10)`
the probability of selecting the first card which is a prime number is
`(4)/(9)`
the probability of selecting two prime numbers is
`(5)/(10)`×
`(4)/(9)`=
`(2)/(9)`