A box contains 3 yellow balls and 7 black balls. One by one, every ball is selected at random without replacement. What is the probability that the fourth ball selected is black?
Choose the correct choice.
A) 3/5  B) 7/10  C) 5/8  D) 2/3  E) 3/7
Each ball has an equal chance (1/10) of being selected fourth.   The probability that a black ball is selected fourth is 7/10.   The answer is 7/10.
<result>B</result>
A box contains 3 yellow balls and 7 black balls. One by one, every ball is selected at random without replacement. What is the probability that the fourth ball selected is black?