in a box of 9 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 ?
p ( neither pen is defective ) = 6 / 9 * 5 / 8 = 5 / 12 the answer is c .
multiply(divide(subtract(9, 3), 9), divide(subtract(subtract(9, 3), const_1), subtract(9, const_1)))