Question 288922
A multiple-choice test has three questions, each with four choices for the answer, of which only one of the choices is correct. What is the probability of guessing correctly on at least one of the questions? The answer is .578 but how do I get that?
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Binomial Problem with n = 3 ; p = 1/4
P(at least one correct) = 1 - P(none correct) 
= 1 - (3/4)^3
= 1 - 0.4219
= 0.5781
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A network executive has to decide on the programming line-up for Thursday night. If there are ten shows to choose from, how many six-show line-ups are possible? Answer s 151,200 how do I get that?
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10P6 = 10!/(10-6)! = 10*9*8*7*6*5 = 151200
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Find the probability of having exactly four girls in seven births. Assume no multiple births and that male and female births are equally likely and independent. Answer is.273 how do I get that? 
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P(4 girls in 7 births) = 7C4(1/2)^4(1/2)^3
= 35(1/2)^7
= 35/128
= 0.273
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Cheers,
Stan H.
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