Posted by daniel on .
An urn contains 4 red and 3 blue marbles. What is the probability when three marbles are selected randomly that all 3 will be red, if we select each marble
a) with replacement
b) without replacement

Math  probability 
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lccc 
Reiny,
with replacement:
prob = (4/7)(4/7)(4/7)
without replacement:
prob = (4/7)(3/6)(2/5)