18 balls are numbered 1 to 18 . a ball is drawn and then another ball is drawn without replacement . what is the probability that both balls have even numbers ?
"p ( 1 st ball is even ) = 9 / 18 p ( 2 nd ball is also even ) = 8 / 17 p ( both balls are even ) = 9 / 18 * 8 / 17 = 4 / 17 the answer is b ."
multiply(divide(add(const_4, const_4), 18), divide(subtract(add(const_4, const_4), 1), subtract(18, 1)))