If I have 3 red marbles and 7 blue marbles and pick and replace marbles with like marbles, what is the probability of picking 3 red marbles in a row?

Question

anonymous · Answer

$$\Big\lgroup\frac{Num_Red}{Total_Marbles}\Big\rgroup*\Big\lgroup\frac{Num_Red}{Total_Marbles}\Big\rgroup*\Big\lgroup\frac{Num_Red}{Total_Marbles}\Big\rgroup$$

anonymous · Answer

Imagine this as 3 independent trials using 3 bags of marbles in a row.   Each bag has 3 of 10 marbles that are red.  The result of one bag is independent of the result of the other bags -- so there is the same fraction, multiplied 3 times for the three seperate bags.