Question 1086162: A speech class has seven freshmen and five sophomores. Three people are selected at random to give speeches in sequence. Find the probability of each of the following. (Round your answers to four decimal places.)
(a) the first is a sophomore, the second is a freshman, and the third is a sophomore
(b) all three are freshmen
(c) the first is a sophomore and the other two are freshmen
Answer by mathmate(429)   (Show Source):
You can put this solution on YOUR website! Question:
A speech class has seven freshmen and five sophomores. Three people are selected at random to give speeches in sequence. Find the probability of each of the following. (Round your answers to four decimal places.)
(a) the first is a sophomore, the second is a freshman, and the third is a sophomore
(b) all three are freshmen
(c) the first is a sophomore and the other two are freshmen
Solution:
Use multiplication rule
7 freshmen+5 sophomores = 12 students.
(a) SFS
P(SFS)=5/12*(7/11)*(4/10)=7/66
(b) FFF
P(FFF)=7/12*6/11*5/10=7/44
(c) SFF
P(SFF)=5/12*7/11*6/10=7/44
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