math
posted by Amy .
In a bag there are red, green, black,and white marbles. If there are 6 red, 8 green, 4 black, and 12 white and one marble is to be selected at random, what is the probability it will be white?
I don't know how to solve these.

12/30 = 2/5
Study this site for more information.
http://www.mathgoodies.com/lessons/vol6/intro_probability.html
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