PROBABILITY MATH
posted by HM .
A bag contains 10 red chips and 12 blue chips. Two chips are selected randomly without replacement from the bag.
What is the probability that the two chips are the same color? Round your answer to 3 decimal places..
Help me find the answer.
Is there another way to answer it without the tree method?

You could pick either 2 reds or 2 blues
prob(2 reds) = (10/22)(9/21) = 15/77
prob(2 blues) = (12/22)(11/21) = 2/7
prob(your event) = 15/77 + 2/7 = 37/77