document.write( "Question 252181: The sales Manager of an Automobile dealer estimated 80% of the new cars delivered by them have no defect and so will not be brought back immediately for repair. He sells a fleet of 10 cars to an important customer. What i»the probability that — (i) No car will be brought back (ii) Exactly two cars will be brought back. (iii) At least two cars will be brought back. \n" ); document.write( "

Algebra.Com's Answer #183980 by edjones(8007) $\"\"$ $\"About$

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Binomial expansion: (a+b)^10=a^10+10a^9b+45a^8b^2+... This is the only part of the expansion that we need.
\n" ); document.write( "Let a=.8, b=.2
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\n" ); document.write( "No car returned: .8^10=.107
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\n" ); document.write( "Exactly 2 returned: 45*.8^8*.2^2=.302
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\n" ); document.write( "At least 2 returned:
\n" ); document.write( "10*.8^9*.2=.268 (exactly 1 returned)
\n" ); document.write( "1-.107-.268=.624 (1-one or none returned)
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\n" ); document.write( "Ed \n" ); document.write( "

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