document.write( "Question 629925: A psychology quiz consists of ten true-or-false questions. If a student knows the correct answer to six of the questions, but determines the answers to the remaining questions by flipping a coin. What is the probability that she will obtain a score of at least 90%? \n" ); document.write( "

Algebra.Com's Answer #396591 by ewatrrr(24785) $\"\"$ $\"About$

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document.write( "Hi,
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document.write( " true-or-false questions... student knows the correct answer to six of them
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document.write( " P(scoring ≥ 90%) = P(getting at least 3 of the remaining 4 correct)
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document.write( " P(x≥3) = P(3) + P(4) = 4C3(.5)^3(.5)^1 + 4C4(.5)^4 \r
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document.write( "Note: The probability of x successes in n trials is: 
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document.write( "P = nCx*  where p and q are the probabilities of success and failure respectively. 
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document.write( "In this case p & q are = 1/2 or .5
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document.write( "nCx =  \n" );
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