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Math Help - 97% confidence interval

  1. #1
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    97% confidence interval

    Hi

    I am stumped - how do you find the z* value for a 97% confidence interval when it is not on the table?
    I know it will be btwn 1.96 (95% confidence) and 2.576 (99% confidence) but I am sure that averaging them is not the answer.
    Any direction is appreciated.
    Thanks in advance.
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  2. #2
    MHF Contributor
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    Re: 97% confidence interval

    this is going to depend on the preferences of your professor. You may be allowed to interpolate between values of your table.

    However i suspect that you have been given 2 versions of the normal table: "cumulative probabilities of the normal distribution" and "percentage points of the normal distribution". You will be able to find an almost exact answer for the 97% interval from the probability table.
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