Probability Basicshard
0:00.0

Two urns, U1U_1 and U2U_2, contain colored marbles. U1U_1 holds 33 red and 22 blue marbles, while U2U_2 holds 22 red and 44 blue marbles. A fair die is rolled; if the result is 11 or 22, a marble is drawn from U1U_1. Otherwise, a marble is drawn from U2U_2. If the drawn marble is red, what is the probability it originated from U1U_1?