document.write( "Question 390351: 18 of a group of 20 people will purchase from a store. If 3 people are selected one at a time, what is the probability all 3 will buy? I can not find the formula to solve! \n" ); document.write( "

Algebra.Com's Answer #276738 by jim_thompson5910(35256) $\"\"$ $\"About$

You can put this solution on YOUR website!
Hint: This is a binomial problem where $\"p=18%2F20=9%2F10=0.9\"$ \r
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\n" ); document.write( "\n" ); document.write( "So if you want the probability that exactly x people will buy, you would use the formula \r
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\n" ); document.write( "\n" ); document.write( "(n C x)*(p^x)*(1-p)^(n-x)\r
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\n" ); document.write( "\n" ); document.write( "where 'n' is the total number of people and n C x is the combination formula\r
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\n" ); document.write( "\n" ); document.write( "n C x = n!/(x!(n-x)!)\r
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\n" ); document.write( "\n" ); document.write( "If you need more help, email me at jim_thompson5910@hotmail.com\r
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\n" ); document.write( "\n" ); document.write( "Also, feel free to check out my tutoring website\r
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\n" ); document.write( "\n" ); document.write( "Jim \n" ); document.write( "

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