a bag contains 4 green and 8 white balls . if two balls are drawn simultaneously , the probability that both are of the same colour is
"drawing two balls of same color from four green balls can be done in 4 c ₂ ways . similarly from eight white balls two can be drawn in ⁸ c ₂ ways . p = 4 c ₂ / ¹ ⁵ c ₂ + ⁸ c ₂ / ¹ ⁵ c ₂ = 17 / 33 answer : e"
add(multiply(divide(8, add(4, 8)), divide(subtract(8, const_1), subtract(add(4, 8), const_1))), multiply(divide(4, add(4, 8)), divide(subtract(4, const_1), subtract(add(4, 8), const_1))))