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Homework Help: Confidence Intervals; Am I correct on these 2 problems?

  1. May 1, 2010 #1
    A random sample of 35 trading days is taken and the volume of a particular stock is recorded to determine whether the mean volume of the stock has changed from its 2007 value of 35.14 million shares. The sample resulted in a mean trading volume of = 39.48. Assuming a population standard deviation of 15.07, compute the margin of error for a 95% confidence interval for m. I got 4.19 Is this correct?

    Also, A random sample of 35 trading days is taken and the volume of a particular stock is recorded to determine whether the mean volume of the stock has changed from its 2007 value of 35.14 million shares. The sample resulted in a mean trading volume of = 39.48. Assuming a population standard deviation of 15.07, calculate a 95% confidence interval for m using a Z interval. I got (38.64, 40.32)
    Is that correct or can it not be computed?
     
  2. jcsd
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