Hello, math_lete!

There are at least two ways to approach this problem . . .

There are 8 purple socks 4 green socks and 4 red socks in a drawer.

Two socks are chosen without replacement.

What is the probability that a pair the same colour is chosen?

Therefore: .

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

There are: possible pairs.

. . There are: ways to get two purple socks.

. . There are: ways to get two green socks.

. . There are: ways to get two red socks.

Hence, there are: . ways to get a matching pair.

Therefore: .