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an urn contains seven red balls and three blue balls a) if three balls are selec

ID: 2956045 • Letter: A

Question

an urn contains seven red balls and three blue balls
a) if three balls are selected all at once, what is the probability that two are blue and one is red.
b) if three balls are selected by pulling out a ball, noting its color and putting it back in the urn before the next selection, what is the probability that only the first and third balls drawn are blue
c) if three balls are selected one at a time without putting them back in the run. what is the probability that only the first and third balls drawn are blue?

Explanation / Answer

total balls = 7+3 = 10 red balls = 7 blue balls = 3 a) probability = 3*(3/10*2/9*7/8) = 126/720 = 0.175 b)probability = 3/10*7/10*3/10 = 0.063 c)probability = 3/10*7/9*2/8 = 42/720 = 0.0583