a bag contains 10 black and 20 white balls . one ball is drawn at random . what is the probability that the ball drawn is white ?
"total number of balls = 10 + 20 = 30 number of white balls = 20 probability of drawing a white ball = 20 / 30 = 2 / 3 answer is c"
divide(add(divide(divide(factorial(20), factorial(subtract(20, const_2))), factorial(const_2)), divide(divide(factorial(10), factorial(subtract(10, const_2))), factorial(const_2))), divide(divide(factorial(add(10, 20)), factorial(subtract(add(10, 20), const_2))), factorial(const_2)))