There are 2 small sweaters, 2 medium sweaters, and 1 large sweater in a bag. what is the probability that lydia randomly pulls a medium sweater out of the bag? write the probability as a percent.

This is the beginning of all probability problems.
Memorize it:

Probability =
       (number of ways to be successful)
divided by
       (total number of possibilities) .

What's the total number of possible ways to pull out one sweater ?
. . . . . There are 5 sweaters in the bag, so 5 total possibilities.

How many ways are there to pull out a medium sweater ?
. . . . . There are 2 medium sweaters in the bag.
. . . . . Lydia might pull out this one, or she might pull out that one.
. . . . . There are 2 ways to pull out a medium sweater.

Probability = 2 / 5  =  40% .

Now you've posted enough of these, and gotten answers with
explanations, so you should be able to do them on your own now.

Ithink if ur looking for a ratio it would be 12: 3