Probability › Drawing from bags › Colour ratios
Draws to see all six unique balls
High school · ●●●○○ 50 pts
A jar contains 66 white balls and 6 unique balls: 1 red, 1 blue, 1 green, 1 purple, 1 yellow and 1 cyan. Balls are drawn one at a time, each ball is returned to the jar after it is drawn, and the colours are recorded. What is the expected number of draws needed until all 6 uniquely coloured balls have been seen at least once?