Alex doesn’t mind what socks he puts on in the morning. He has a pair of red socks and a pair of blue socks. Each morning he just takes out the first two socks he finds. So some mornings he wears a pair of red socks and some mornings he wears a pair of blue socks. But some mornings he wears a ‘silly pair’ consisting of one red and one blue sock.
If he gets a pair of green socks as well, how many different pairs of socks, silly and otherwise, can he wear?
Solution
Alex can make up six pairs of socks altogether.
If we make a list we find:
- red, red
- red, blue
- red, green
- blue, blue
- blue, green
- green, green
Extension
How many different pairs of socks, silly and otherwise, could Alex wear if he had six normal pairs of socks that were red, blue, green, white, black, and yellow?
What if he had 100 differently coloured socks?