In a box of 10 pens, a total of 3 are defective. If a customer buys 2 pens selected at random from the box, what is the probability that neither pen will be defective?  Answers
A) 4/9
B) 5/11
C) 7/15
D) 9/22
E) 12/35
# defective pens = 3   # good pens = 7   Probability of the 1st pen being good = 7/10   Probability of the 2nd pen being good = 6/9   Total probability = 7/10 * 6/9 = 7/15   The answer is 7/15.
<result>C</result>
In a box of 10 pens, a total of 3 are defective. If a customer buys 2 pens selected at random from the box, what is the probability that neither pen will be defective?