Trace: • answer
wiki:donuts:winter2015:blackcards:answer
Answer
2/3
Number the black cards 1-3. The black cards numbered 1 and 2 are in pile together, and card number 3 is in the pile with the red card. You know that your pile has one black card on top, so the possible combinations are
| B1 | B2 | B3 |
| B2 | B1 | R |
With three total outcomes, two of them have a black card on bottom. The probability of the bottom card being black is 2/3.
wiki/donuts/winter2015/blackcards/answer.txt · Last modified: 2015/02/25 11:06 by jmb438