document.write( "Question 1072879: A container contains 10 diesel engines. The company chooses 6 engines at​ random, and will not ship the container if any of the engines chosen are defective. Find the probability that a container will be shipped even though it contains 2 defectives if the sample size is 6.\r
\n" ); document.write( "\n" ); document.write( "Can someone please breakdown the steps to solve this. This is an online class and the help feature isn't explaining how to get the numbers needed to solve it. Thank you
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Algebra.Com's Answer #687735 by KMST(5328)\"\" \"About 
You can put this solution on YOUR website!
I am baffled by the phrase \"if the sample size is 6\" at the end of the problem.
\n" ); document.write( "The problem said before that the company chooses 6 engines out of the 10 in the container. What is that phrase about sample size for?
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\n" ); document.write( "Anyway, there are
\n" ); document.write( "different possible sets of 6 engines that can be chosen.
\n" ); document.write( "NOTE: That is combinations of 10 taking 6 at a time.
\n" ); document.write( "Your online class may use a symbol with a \"C\" for combinations,
\n" ); document.write( "instead of the \"%28matrix%282%2C1%2C10%2C6%29%29\" notation I used.
\n" ); document.write( "
\n" ); document.write( "There are only \"%28matrix%282%2C1%2C8%2C6%29%29=%28matrix%282%2C1%2C8%2C2%29%29=8%2A7%2F2=4%2A7=28\"
\n" ); document.write( "sets of 6 good engines that can be made with the
\n" ); document.write( "\"10-2=8\" good engines in that container that has \"2\" defective ones.
\n" ); document.write( "As a fraction that is \"28%2F210=highlight%282%2F15%29\" ,
\n" ); document.write( "and that is the probability that the set of 6 engines chosen does not have a defective one.
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\n" ); document.write( "FORMULAS:
\n" ); document.write( "I do not like formulas as a substitute for understanding concepts.
\n" ); document.write( "The concept that is relevant to this problem is the concept of combinations.
\n" ); document.write( "The number ways of choosing a set of \"6\" engines
\n" ); document.write( "out of a set of \"10\" engines, can be seen as
\n" ); document.write( "\"%28matrix%282%2C1%2C10%2C6%29%29\" , the number of ways to pick the chosen \"6\" ,
\n" ); document.write( "or \"%28matrix%282%2C1%2C10%2C4%29%29\" , the number of ways of selecting the (\"4\" not chosen.
\n" ); document.write( "\"%28matrix%282%2C1%2C10%2C4%29%29=10%2A9%2A8%2A7%2F%284%2A3%2A2%29=10%2A3%2A7=210\" ,
\n" ); document.write( "with \"4\" factors in numerator, and \"4\" factors in denominator,
\n" ); document.write( "makes for an easier calculation than
\n" ); document.write( "\"%28matrix%282%2C1%2C10%2C6%29%29=10%2A9%2A8%2A7%2A6%2A5%2F%286%2A5%2A4%2A3%2A2%29\" .
\n" ); document.write( "Below are the formulas and why they are the way they are.
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\n" ); document.write( "Permutations of \"k\" items taking all \"k\" is
\n" ); document.write( "the number of different ordered lists of \"k\" items that can be made
\n" ); document.write( "from all \"k\" items of a set of \"k\" different items is
\n" ); document.write( "\"factorial\"\"k\"\"%22=%22\"\"highlight%28k%21=k%2A%28k-1%29%2A%28k-2%29%2A%22...%22%2A3%2A2%2A1%29\" ,
\n" ); document.write( "because there are
\n" ); document.write( "\"k\" ways to pick the first item for the list,
\n" ); document.write( "\"%28k-1%29\" ways to pick the second item for the list,
\n" ); document.write( "\"%28k-2%29\" ways to pick the third item for the list,
\n" ); document.write( "and so on, until you have
\n" ); document.write( "\"3\" ways to pick one of the \"3\" items not picked before,
\n" ); document.write( "\"2\" ways to pick one of the \"2\" items not picked before,
\n" ); document.write( "and \"1\" choice for the last item on the list.
\n" ); document.write( "That \"k%21\" is the number of options a teacher would have
\n" ); document.write( "to randomly line up all \"k\" students in a class.
\n" ); document.write( "
\n" ); document.write( "Permutations of \"n\" items taking \"k\" of them is
\n" ); document.write( "the number of different ordered lists of \"k\" items that can be made
\n" ); document.write( "from the \"n\" different items in a set.
\n" ); document.write( "That number is
\n" ); document.write( "
\n" ); document.write( "That is a product of \"k\" factors.
\n" ); document.write( "That is the number of options a teacher would have to randomly select
\n" ); document.write( "a line of \"k\" of the \"n\" students in the school.
\n" ); document.write( "The teacher would have
\n" ); document.write( "\"n\" choices for the first student in the line,
\n" ); document.write( "\"%28n-1%29\" choices for the second student in the line,
\n" ); document.write( "\"%28n-2%29\" choices for the third student in the line,
\n" ); document.write( "and so on, until there are \"%28n-k%2B1%29\" choices possible
\n" ); document.write( "for the last of the \"k\" picks.
\n" ); document.write( "For the last of the \"k\" picks,
\n" ); document.write( "there are \"%28n-k%2B1%29\" students wishing (or dreading) to be the last pick.
\n" ); document.write( "(After that last pick, there are \"%28n-k%29\" students left out,
\n" ); document.write( "disappointed, or relieved that they were not picked).
\n" ); document.write( "You can see how factors in the factorials ratio simplify leaving only \"k\" factors.
\n" ); document.write( " .
\n" ); document.write( "
\n" ); document.write( "Combinations of \"n\" items taking \"k\" of them is
\n" ); document.write( "the number of different sets of \"k\" items that can be made
\n" ); document.write( "from the \"n\" different items in a set.
\n" ); document.write( "The formula for combinations of \"n\" taken \"k\" at a time is
\n" ); document.write( " .
\n" ); document.write( "It is the number of possible sets \"k\" of the \"n\" students in the school that can be made.
\n" ); document.write( "There are \"n%21%2F%28n-k%29%21\" possible lists,
\n" ); document.write( "but they are not going to be lined up, order does not matter.
\n" ); document.write( "Any \"1\" set of \"k\" students will be listed in a different order in \"k%21\" lists,
\n" ); document.write( "but it is just \"1\" set,
\n" ); document.write( "so the \"n%21%2F%28n-k%29%21\" possible lists boil doen to
\n" ); document.write( "\"n%21%2F%28%28n-k%29%21k%21%29\" possible sets.
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