A box contains 4 red chips and 5 blue chips. If two chips are selected at random without replacement, what is the probability that the chips are different colors?	Choices.
A) 1/2	B) 5/9	C) 7/12	D) 2/3	E) 7/10
Total selection ways: 9C2=9!/5!4!=36   Selecting one blue chip out of two: 5C1=5!/4!1!=5   Selecting one red chip out of four: 4C1=4!/1!3!=4   Thus, (5C1*4C1)/9C2=(5*4)/36=20/36=5/9=5/9
<result>B</result>
A box contains 4 red chips and 5 blue chips. If two chips are selected at random without replacement, what is the probability that the chips are different colors?