Tell us what’s happening:
Test 3 has incorrect expected value. I’ve enumerated the possibilities manually and counted 2,088 possible ways to draw at least 2 blue balls and one green ball when drawing 4 balls randomly without replacement from a hat initialized with 3 blue balls, 2 red balls, and 6 green balls. With 7920 total possible draws (11 * 10 * 9 * 8) that means the probability should be 0.26363636… The tests look for a probability of 0.272 (delta 0.01), so the actual expected result is very close to the edge of the accepted range.
Challenge: Probability Calculator
Link to the challenge: