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Math Help - help with a sampling variance problem

  1. #1
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    Oct 2009
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    help with a sampling variance problem

    I cannot figure out this problem for the life of me. It says:
    A process produces batches of a chemical whose impurity concentration follows a normal standard distribution with a variance of 1.75. A random sample of 20 of these batches is chosen. Find the probability that the sample variance exceeds 3.10

    I know this is simple but iv tried the formula (n-1)S^2/sigma^2 every way, and have even looked through the chi square table and tried to reverse engineer an answer with no luck. Can someone please help me
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  2. #2
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    please see attached
    hope I understand ur problem right
    Attached Files Attached Files
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