SOLUTION: a firm which conducts consumer surveys by mail has found that 30 percent of those families receiving a questionnaire will return it. in a survey of 10 families, what is the probabi

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Question 1192953: a firm which conducts consumer surveys by mail has found that 30 percent of those families receiving a questionnaire will return it. in a survey of 10 families, what is the probability that (1) exactly five families will return the questionnaire.(ii) between 3 to 5 five families (inclusive) will return the questionnaire (iii) exactly 10 will return the questionnairo?
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
exactly 10 will return is 0.3^10=0.0000059 or 5.9 x 10^(-6)
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5 families is 10C5*0.3^5*0.7^5=252*0.3^5*0.7^5=0.1029
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4 families is 10C4=210*0.3^4*0.7^6=0.2001
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3 families is 10C3=120*0.3^3*0.7^7=0.2668
Total of those three is 0.5698.