Only 4 because the only way he cant get a pair is if he picks up a different colour to the previous sock, so by the fourth he will have picked up at two of at least one colour
Answer: 493,700,000
Step-by-step explanation:
Answer:
2nd 3rd and last option
Step-by-step explanation:
2.
3.
6.
The definition is pretty simple:

So, we only have to sum the expressions:
