Question 328408
a) P(4 bad)={{{(0.03)(0.03)(0.03)(0.03)=8.1x10^(-7)}}}
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b) P(4 good)={{{(0.97)^4=0.8853}}}
Look at all of the possible combinations of exactly 2 bad (G-good, B-bad)
GGBB
GBGB
GBBG
BGGB
BGBG
BBGG
There are 6 of them.
Their individual probabilities are {{{P=(0.97)^2(0.03)^2=0.00084681}}}
Since there are 6 of them,
P(exactly 2 bad)={{{6(0.00084681)=0.00508}}}
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c) P(4 good)={{{(0.97)^4=0.8853}}}